mtd: msm_qpic_nand: Add clock gating and bus bandwidth voting

QPIC NAND has three clocks viz. gcc_qpic_system_clk, qcc_qpic_ahb_clk,
and gcc_qpic_clk. Need to set_rate and enable only qpic_clk and then
RPM will enable system_clk and ahb_clk as well.

But the clocks are always on even when there are no requests to process.
So add support to gate/ungate the clocks accordingly. Also add support
to vote and unvote the bus bandwidth for better performance.

But if the clock is set and immediately suspend is triggered the clocks
would remain still enabled along with bus vote. So introduce both the PM
and Runtime PM suspend/resume to handle these cases as well.

CRs-Fixed: 488510
Change-Id: I373b39e15f6f7e2c10a8ebe182992743a1cb7838
Signed-off-by: Pratibhasagar V <pratibha@codeaurora.org>