[zircon][aml-sd-emmc] Add timeout for commands

sdmmc layer waits on command completions sychronously. Currently the
cmd timeout is 0, and that means the controller waits forever
for the command to complete. This changeset avoids blocking sdmmc
if a single command is not completed within the timeout.
Most likely something else has gone wrong if the command is not
completed within this time.

Test: Booted vim2 with zircon. Tested R/W on the emmc using dd and
iotime. sdio probe is succesful. SDIO Reads and Writes are successful
With https://fuchsia-review.googlesource.com/c/garnet/+/187629/7.

Change-Id: I08dd8d82b6f3ae91544d63f5123c0620e3bbef10

[zircon][sdio]Fix multiblock support and re-enable it

When submitting a multiblock CMD53, the config register in the
controller should be updated to reflect the new block length.
This changeset also fixes how the multiblk command is submitted
in PIO mode.

Test: Modified the block size of sdio fn0 to be 8 and read 16 bytes of data
on vim2 with both dma and pio mode. Prior to this change the read fails.
More testing is in progress

Change-Id: Iefce824d547de88bebd468f1d16c5f2177bfb194

[zircon][sdio]Add UHS support

This changeset adds support for ultra high speed for sdio.
Astro fails the read commands when frequency is more than 25Mhz,
mostly related to the PORT issues on it, which needs further investigation.

Test: Tested SDIO probing on Vim2 and Astro.

Change-Id: Ibb6cb4f79203ea76b300c3f0ea6fe06f772bcad5

[zircon][aml-sd-emmc] Get driver metadata from board dirver

This changeset gets information whether a board supports dma. While,
there it also resolves a bug in the PIO mode write.

Change-Id: I37872ea9763f2d1da30608c2c6524d37b48bc69e

[zircon][amlogic][sdmmc] Reduce to even lower frequency when tuning fails

The new vim2 boards return CRC errors during read operations at the
existing frequency. The tuning process actually tries to figure out the
optimum frequency by lowering the frequency and resending the tuning
command. However at times the tuning commands succeed but the read
command fails with that frequency. This changeset descreases the
frequency more when a tuning failure occurs so that the read commands
that follow succeed.

Change-Id: Iff96c3e8d5cda303e293be5f295dd616ee65864b

[zircon][amlogic][sd-emmc] Add PIO mode support

The SDIO instance PORTA of the amlogic controller does not support DMA.
This change adds PIO support for the driver. The use_dma flag is used by the amlogic
controller for command submission as well as data as compared to the
sdhci on x64. In PIO mode, the controller reads the descriptors from the SRAM region of
the mmio space and data from the ping-pong buffers. For SDHCI on X64, the use_dma
flag is ignored during command submission and used only during data.
While in sdmmc, this changeset also fixes the issue of unmap when sdmmc
does not use dma.

Change-Id: I8d6dc95acb6405e1f89511376a68a044bbf0ece4

[dev] Rename system/dev/soc to system/dev/lib

Change-Id: I9ebed28956566cc71bdfe142bff633ef50f8a9dc