morello: Use common sc_pll module

Remove the private PLL modules and any references to
them from Morello, and add the necessary changes
and config data to use the SCP core sc_pll module instead.

Signed-off-by: Vishnu Satheesh <vishnu.satheesh@arm.com>
Change-Id: Ic6370fc26b0137fcc21d5e1442da793b96948916