MdeModulePkg:BaseSpiHcPlatformLib: Adding NULL lib instance

Adding NULL SpiHcPlatformLib instance. This library is responsible for
handling the low level details of the SPI host controller. Since this is
platform specific this library will be dependent on OEM SPI
implementation. The SPI host controller layer will utilize this library
for SPI bus transactions.

Bugzilla #4753

Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Abner Chang <abner.chang@amd.com>
Cc: Abdul Lateef Attar <AbdulLateef.Attar@amd.com>
Signed-off-by: Brit Chesley <brit.chesley@amd.com>
Acked-by: Abner Chang <abner.chang@amd.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

MdeModulePkg/MdeModulePkg.dec

@@ -169,6 +169,11 @@
   #
   ImagePropertiesRecordLib|Include/Library/ImagePropertiesRecordLib.h
 
+  ##  @libraryclass   Platform SPI Host Controller library which provides low-level
+  #                   control over the SPI hardware
+  #
+  SpiHcPlatformLib|Include/Library/SpiHcPlatformLib.h
+
 [Guids]
   ## MdeModule package token space guid
   # Include/Guid/MdeModulePkgTokenSpace.h