msm: clock-8960: Do hwcg for vcodec_axi_{a,b}_clk

Vcodec has three software controlled axi clocks on 8960.
Previously we would hide the a and b clocks from users of the clk
APIs and mark a and b as dependents of vcodec_axi; essentially
combining all three clocks into one.

With dynamic clock gating we need to disable and enable dynamic
clock gating along with the reset assertion and deassertion. We
can't achieve this with the current clk_reset() code as it relies
on the hardware gating register to be the same for all three
clocks. Now that the footswitch driver can reset arbitrary clocks
support dynamic clock gating for vcodec by having the footswitch
driver call clk_reset on all three axi clocks on 8960.

Change-Id: If59ae47d2881267c06b7acb0a13d0302d31396bf
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>