ArmPkg: Fix data type used for GicDistributorBase

The data type used by variables representing the GicDistributorBase has
been inconsistently used in the ArmGic driver and the library.  The PCD
defined for the GIC Distributor base address is UINT64.  However, the
data types for the variables used is UINTN, INTN, and at some places
UINT32.

Therefore, update the data types to use UINTN and add necessary
typecasts when reading values from the PCD. This should then be
consistent across AArch32 and AArch64 builds.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>

ArmPkg/Drivers/ArmGic/ArmGicCommonDxe.c

@@ -1,6 +1,6 @@
 /*++
 
-Copyright (c) 2013-2017, ARM Ltd. All rights reserved.<BR>
+Copyright (c) 2013-2023, Arm Ltd. All rights reserved.<BR>
 
 SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -61,7 +61,7 @@ GicGetDistributorIcfgBaseAndBit (
 
   RegIndex    = Source / ARM_GIC_ICDICFR_F_STRIDE; // NOTE: truncation is significant
   Field       = Source % ARM_GIC_ICDICFR_F_STRIDE;
-  *RegAddress = PcdGet64 (PcdGicDistributorBase)
+  *RegAddress = (UINTN)PcdGet64 (PcdGicDistributorBase)
                 + ARM_GIC_ICDICFR
                 + (ARM_GIC_ICDICFR_BYTES * RegIndex);
   *Config1Bit = ((Field * ARM_GIC_ICDICFR_F_WIDTH)