ANDROID: Add padding for crypto related structs in UFS and MMC

Add padding to ufshcd_host and ufshcd_hba_variant_ops UFS, and mmc_host
in MMC to allow expansions in future if necessary, while keeping the
ABI stable. These fields are only for the purposes of keeping the ABI
stable, and in particular are *NOT* for vendor use.

Bug: 153512828
Bug: 144046242
Bug: 137270441
Change-Id: I7b780680bf3e8a3121c6f77b35a2a16d41f3bea6
Signed-off-by: Satya Tangirala <satyat@google.com>