msm: clock: Remove the clk_set_min_rate() API and set_min_rate ops

This API is now unused. Since it is proprietary and not a generic
kernel API, remove it. Also remove use of the min_rate ops for all
clock except proc_comm clocks, for which CLKFLAG_MIN is still used.

Change-Id: I54e9baeef0058982c31a0752343dd54189eeaa04
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>