ArmPlatformPkg/NorFlashDxe: Fixed LBA for FVB

FVB (for instance for UEFI Variable) might not be at the
start of the NOR Flash. 'Lba' needs to be fixed up for it.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>



git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15532 6f19259b-4bc3-4df7-8a09-765794883524