In omap4, there is no explicit configuration register to enable mailbox clocks.
Defining dummy clock for mailbox clock module to keep the mailbox driver
backward compatible with previous omaps.
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Acked-by: Benoît Cousson <b-cousson@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>