Currently the types of casting mismatch with TD MMIO read 1, 2 and 4
bytes, that might introduce potential issues. So fix the types as
conventional MmioRead[8|16|32] does.
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Signed-off-by: Zhiquan Li <zhiquan1.li@intel.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>