Vlv2TbltDevicePkg/AcpiPlatform: Change Size type to UINTN

Vlv2TbltDevicePkg/AcpiPlatform: Change Size type to UINTN

Change the type of the local variable Size in the function
AcpiPlatformEntryPoint() from UINT32 to UINTN.  This local
variable is passed into the function ReadSection() that returns
a value of type UINTN.  Using type UINT32 can potentially
corrupt an adjacent local on the stack.

Cc: Zailiang Sun <zailiang.sun@intel.com>
Cc: Yi Qian <yi.qian@intel.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Zailiang Sun <zailiang.sun@intel.com>
Reviewed-by: Yi Qian <yi.qian@intel.com>