ArmPlatformPkg: Changed memory model for the stacks

In the previous version, every cores had the same stack size.
To avoid to waste memory with secondary core stacks, the primary core stack
size is now different from the secondary cores stack size.

These are the Stack PCDs and their default values:

gArmPlatformTokenSpaceGuid.PcdCPUCoresSecStackBase|0
gArmPlatformTokenSpaceGuid.PcdCPUCoreSecPrimaryStackSize|0x10000
gArmPlatformTokenSpaceGuid.PcdCPUCoreSecSecondaryStackSize|0x1000

gArmPlatformTokenSpaceGuid.PcdCPUCoresSecMonStackBase|0
gArmPlatformTokenSpaceGuid.PcdCPUCoreSecMonStackSize|0x1000

gArmPlatformTokenSpaceGuid.PcdCPUCoresStackBase|0
gArmPlatformTokenSpaceGuid.PcdCPUCorePrimaryStackSize|0x10000
gArmPlatformTokenSpaceGuid.PcdCPUCoreSecondaryStackSize|0x1000

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12415 6f19259b-4bc3-4df7-8a09-765794883524