n1sdp: Use common sc_pll module

Remove the private PLL modules and any references to
them from N1SDP, 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: I7359fb0eb88befe44ea8a2d4f2ffcb1d3e2e91ad