feat(tc): add support for configuring DSU settings

This patch allows tc platforms to update DSU
CLUSTERPWRDN_EL1 and CLUSTERPWRCTLR_EL1 settings.
TC22 and TC23 use the DSU-120. Currently
we use the reset values as default settings as
per the DSU-120 TRM.

Reference: https://developer.arm.com/documentation/102547/0201

Change-Id: I48e0b5bd5881612e9b8b804948260f69c25c34d9
Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
2 files changed