clk: mvebu: cp110: make failure labels more meaningful

In preparation to the addition of a new clock, rename the goto labels
used to handle the failure cases using a name related to the failure
cause. This will allow to insert additional failing cases without
renaming all the labels.

Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>