MdePkg: Add definitions for the SPI protocols introduced in PI 1.6.

MdePkg: Add definitions for the SPI protocols introduced in PI 1.6.

This commit adds header files for the SPI protocols introduced in the
UEFI PI 1.6 specification, as well as their GUIDs to MdePkg.dec.

EFI_SPI_TRANSACTION_TYPE assumes an enum with its members ordered the
way they are listed in the specification, as there are no values given
explicitely.
EFI_LEGACY_SPI_CONTROLLER_GUID assumes the character 'l' used in the
specification was meant to be '1'.

V2:
- Fixed LegacySpiFlash.h's header guard.
- Fixed LegacySpiSmmController's GUID name.
- Removed EFI_SPI_NOR_FLASH_PROTOCOL_LF_READ_DATA as it's unused.
- Added the missing SpiSmmNorFlash header.
- Fixed all file endings to be CRLF.
- Removed trailing whitespaces.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Marvin Haeuser <Marvin.Haeuser@outlook.com>
Reviewed-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>