- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC: r270885, r270948

- Nuke unused sdhci_softc.
- Static'ize sdhci_debug local to sdhci.c.
- Const'ify PCI device description strings.
- Nuke redundant resource ID members from sdhci_pci_softc.
- Nuke unused hw.sdhci_pci.debug tunable.
- Add support for using MSI instead of INTx, controllable via the tunable
hw.sdhci.enable_msi (defaulting to on) and tested with a RICOH R5CE823 SD
controller.
- Use NULL instead of 0 for pointers.

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add hooks for plugging platform-provided transfer backend.

In order to use platorm backend hardware driver should
impement three methods:
- platform_start_transfer and platform_finish_transfer
to start and finish transfer
- platform_will_handle - check whether transaction is
suitable for backend. If not - driver will fall back
to PIO mode.

Submitted by: Daisuke Aoyama <aoyama at peach.ne.jp>
Approved by: ian@

Various timing-related fixes:

- Replace divisor numbers with more descirptive names
- Properly calculate minimum frequency for SDHCI 3.0
- Properly calculate frequency for SDHCI 3.0 in mmcbr_set_clock
- Add min_freq method to sdhci_if.m and provide default
implementation. By re-implementing this method hardware
drivers can control frequency controller operates when
executing initialization sequence

Split sdhci driver in two parts: sdhci and sdhci_pci.
sdchi encapsulates a generic SD Host Controller logic that relies on
actual hardware driver for register access.

sdhci_pci implements driver for PCI SDHC controllers using new SDHCI
interface

No kernel config modifications are required, but if you load sdhc
as a module you must switch to sdhci_pci instead.