ArmPlatformPkg/ArmRealViewEbPkg: Use NorFlashDxe and enable variables services

ArmPlatformPkg/ArmRealViewEbPkg: Use NorFlashDxe and enable variables services

The ARM RealView EB (hardware and RTSM) supports the same NOR Flash controller
as the ARM Versatile Express.
Add the implementation of the NorFlashPlatformLib for ArmRealViewEb.

Remove the Firmware Volume Block raw data used to enable environment variables on
ARM RealView EB from the FDF file to use the NOR Flash driver.

Replace the variable service emulation by the version using Firmware Volume Block.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11747 6f19259b-4bc3-4df7-8a09-765794883524