msm: acpuclock: Rename acpuclock-7201.c to acpuclock-7627.c

This acpuclock driver hasn't supported 7201 or 7x25 for some time.
In fact, all of the APIs within it are already named after 7627
(the first target it does support) and not 7201.

Rename the file to make it clear that these older devices are not
supported.

Change-Id: Ib453864c67d6069ce4fbe069718a5d78fdfb0cab
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>