fvp: Remove unnecessary default case
fvp: Remove unnecessary default case

The default case is impossible to hit as the `power_level`
is already checked earlier.  Avoids a clang warning.

Change-Id: I707463c843adc748ee9aa1d2313f9ab7dab3a8ab
Signed-off-by: dp-arm <5172875e934a989df22d22726b6d9d921b91fbdd@arm.com>

lsigithub/arm-trusted-firmware_public,achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware,lsigithub/arm-trusted-firmware_public