MdeModulePkg/Ufs: ensure the DBC field of UTP PRDT is dword-aligned

MdeModulePkg/Ufs: ensure the DBC field of UTP PRDT is dword-aligned

According to UFS Host Controller Spec(JESD223), the bits 1:0 of this
DataByteCount field shall be 11b to indicate Dword granularity.

But the size of UFS Request Sense Data Response defined in UFS Spec
(JESD220C) is 18 which is not Dword aligned, we would have to round
down to the multiple of 4 to fill the DBC field to avoid bring issue
on some UFS HCs.

Cc: Hao Wu <hao.a.wu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Feng Tian <feng.tian@intel.com>
Reviewed-by:   Hao Wu <hao.a.wu@intel.com>