msm: emac: Add support to vote for bus bandwidth scaling

EMAC as  a Bus client on PCNOC bus has to vote for
Bus scaling to achieve required throughput and to
avoid bus access error on PCNOC in absence
of Bus scaling vote from Bus client and PNOC clock
gating is enabled.

Change-Id: Iae08aba1d1aa5ab81d453820148b8a6abf0ea4cc
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>