Some apcs mailbox devices supports a clock driver, the compatible
strings of devices supporting clock driver along with the clock driver
name are maintained in a separate structure within the mailbox driver.
And the clock driver is added based on device match.

With increase in number of devices supporting the clock feature move the
clock driver name inside the driver data. so that we can use a single
API to get the register offset of mailbox driver and clock driver name
together, and the clock driver will be added based on the driver data.
Signed-off-by: Sivaprakash Murugesan <sivaprak@codeaurora.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>