[dev][aml-axg-gpio] Refactor and add support for Amlogic S905D2

Change-Id: Ib8704a5a55d9b9655a3ad55c9f05b22403563f5c

[gauss] Configure USB PHY mode properly on USB connect and disconnect

Fixes hang in USB stack when unplugging a USB device

ZX-1389 #done

Change-Id: I6b3393fa8ac8829485ca74a539e6dbb31b0aece9

[gauss][board] refactor audio out dev

Change-Id: Iaffc4e01af94bbc682a57279e83b941c9b3af4e7

[gauss] Refactor gauss platform bus driver

Move platform bus support driver for gauss to system/dev/board/gauss.

Also move gauss i2c test driver to system/dev/board/gauss.

Amlogic A113 specific code remains in system/dev/soc/aml-a113,
which is now a static library.

Later we may move code (i2c, gpio, etc) that works for other Amlogic SOCs
may get broken out into separate libraries.

Change-Id: If2133824563be3086a8ea41064e5955d6ae4d609