msm: acpuclock: Fix error path in multicore targets

Several acpuclock drivers have inherited the same error path bug in
acpuclk_set_rate(). If an invalid cpu is passed as an argument to
these functions, they should return immediately instead of jumping to
the 'out' label, which attempts to unlock a mutex which has never
been acquired.

Change-Id: I47b9709605673a5200caf73a2f2a5086fde63efe
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>