NOUPSTREAM: ANDROID: scsi: SCSI related vendor hooks

Add a 'fill_prdt' Android vendor hook so that UFS platform drivers can
initialize variant-specific PRDT fields.

This is needed for FMP support.

[CPNOTE: 03/06/21] Lee: Vendor related code - maintain forever

Squash:
  NOUPSTREAM: ANDROID: scsi: ufs: add a hook to prepare command
  NOUPSTREAM: ANDROID: scsi: ufs: add a hook to add sysfs entries
  NOUPSTREAM: ANDROID: scsi: ufs: add hooks to monitor stats of UFS traffic
  NOUPSTREAM: ANDROID: scsi: ufs: add hooks to track ufs commands

Bug: 166139333
Bug: 162257402
Bug: 181359082
Bug: 158050260
Bug: 172874931
Bug: 172305874
Bug: 176940922
Change-Id: Icd07b5e475555ef3eaa0ae9e18a1ae9a4b981679
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Lee Jones <joneslee@google.com>