MdeModulePkg/SdMmcPciHcDxe: call SdMmcFreeTrb() to complete sync operation

MdeModulePkg/SdMmcPciHcDxe: call SdMmcFreeTrb() to complete sync operation

Currently, we complete a synchronous operation without unmapping the
DMA mappings, and free the pages using FreePages () rather than calling
EFI_PCI_IO_PROTOCOL::FreeBuffer. This is simply incorrect, but it also
breaks non-coherent DMA as well as DMA protection and/or memory encryption
so let's do it correctly and call SdMmcFreeTrb() instead.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>