scsi: ufs: export set_bus_vote ops

The bus bandwidth vote is required to be done before the bus clocks
are enabled, hence separate the bus voting from vendor specific
setup clocks that is called after the ufs core clocks are enabled.

Change-Id: I5148ec4ce55a00f5130a60d0c088b3f0218d2261
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>