IPQ40xx: clk: dont always return 0

Currently the driver will go through the clock ID-s and set/enable them as needed.
But if the ID is unknown it will fall through the switch case to the default case which will always return 0.

This is not correct and default cases should return a error code since clock ID is unknown.
So lets return -EINVAL instead.

Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Cc: Luka Perkov <luka.perkov@sartura.hr>