drivers: llcc: Support targets that can write to llcc registers

For older targets, it is possible that they are not allowed
to configure certain llcc registers, as that is handled by
the secure side. However, this is not the case for newer
targets, and as such, they must configure these registers
according to the contents of the SCT table, while keeping in
mind that older targets may not have these capabilities.
Allow configuration of registers to enable capacity based
allocation and power collapse retention for capable targets.

Change-Id: I2106f98812a9369f1fdb7e20453741f1375c0a58
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>