Assert if power level value greater then PSCI_INVALID_PWR_LVL
Assert if power level value greater then PSCI_INVALID_PWR_LVL

Signed-off-by: Deepika Bhavnani <095849dccdc2dcad20acc908a1b020ea4af994c4@arm.com>
Change-Id: I4a496d5a8e7a9a127cd6224c968539eb74932fca

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