ArmPkg/ArmDmaLib: Fixed the calculation of the Base Address of the Buffer

The former calculation 'ALIGN_VALUE(*DeviceAddress - BASE_4KB - 1,BASE_4KB)' did
not return the lowest aligned address.

Example:
*DeviceAddress = 0xB000C001;
*DeviceAddress - BASE_4KB - 1 = 0xB000B000;
Aligned value = 0xB000B000 + ((0x1000 - 0xB000B000)) & 0xFFF) = 0xB000B000
... while we where expected 0xB000C000.

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@14618 6f19259b-4bc3-4df7-8a09-765794883524