Merge remote-tracking branch 'aosp/upstream-hikey-aosp' into HEAD

Update to upstream OpenPlatformPkg branch.

Specifically:
o Drivers/DwUsbDxe: fix hang in fastboot boot command
o Platforms/HiKey960: Support 4G or more memory space for RAM
o Platforms/HiKey960Dxe: check whether reboot reason updated
o Platforms/HiKey960Dxe: check flag before clearing virtual key

Signed-off-by: John Stultz <john.stultz@linaro.org>