MdeModulePkg/SdMmcPciHcDxe: Use 16/32-bit IO widths

MdeModulePkg/SdMmcPciHcDxe: Use 16/32-bit IO widths

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1537

Use 16-bit and 32-bit IO widths for SDMMC MMIO to prevent all register
accesses from being split up into 8-bit accesses.

The SDHCI specification states that the registers shall be accessible in
byte, word, and double word accesses. (SD Host Controller Simplified
Specification 4.20 Section 1.2)

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>
Reviewed-by: Hao Wu <hao.a.wu@intel.com>