Juno: Enable non-secure accesses to the system timer ...

This patch programs the CNTCTLBase.CNTNSAR to give non-secure access
to timer frame 1. It also programs the CNTCTLBase.CNTACR1 to give
access to all the timer registers in this frame.

Change-Id: Ia10c9572a70bd5910031de1994116bb9314efd80

Conflicts:

	plat/juno/bl31_plat_setup.c
	plat/juno/platform.h

juno: Add a check to verify BL2 to BL31 plat. param ...

This concerns only debug builds. In BL2, we now pass a special value
to BL3-1 through x1. In BL3-1, we check that we receive the correct
value. This ensures that any platform set value is correctly passed
from BL2 to BL3-1.

Change-Id: Icb94d0e99ca445dcbe574a7d5e291659bba2209e

juno: Split platform.h into separate headers ...

Change-Id: Ic0abaa12f13a6a1dead41c914c6c103a65f273fa