feat(tc0): update Matterhorn ELP DVFS clock index
feat(tc0): update Matterhorn ELP DVFS clock index

This allows the the Matterhorn ELP Arm core to operate at its
designated OPP.

Signed-off-by: Usama Arif <2c149411f3e2627c4e078c64c194672b53885363@arm.com>
Change-Id: I7ccef0cfd079d630c3cfe7874590bf42789a1dca

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware