ArmPlatformPkg/SP804Timer: Remove the SP810 System Controller dependency

ArmPlatformPkg/SP804Timer: Remove the SP810 System Controller dependency

The SP804 drivers must not consider the presence of the SP810 System Controller
on the platform. The SP810 was used to enable the SP804 Dual Timers on ArmVExpress.
It is the role of the Platform specific driver to enable to the SP804 dual timers
if required.

The former SP810 initialization code has moved to ArmPlatformLib for ArmRealViewEb
and ArmVersatileExpress.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11744 6f19259b-4bc3-4df7-8a09-765794883524