ArmPlatformPkg: Introduce ArmPlatformInitialize() function

ArmPlatformPkg: Introduce ArmPlatformInitialize() function

This function is responsible to handle all the specific platform code that must
be run in secure world to initialize some controllers.

ArmPlatformPkg/Sec: Move the L2x0 initialization to ArmPlatformLib

The L2x0 controller must be initialized in secure world. Move its initialization
into the ArmPlatformInitialize() of the Cortex A9x4 Core Tile PlatformLib.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11476 6f19259b-4bc3-4df7-8a09-765794883524