media: venus: core,pm: Vote for min clk freq during venus boot

Vote for min clk frequency for core clks during prepare and enable clocks
at boot sequence. Without this the controller clock runs at very low value
(9.6MHz) which is not sufficient to boot venus.

Signed-off-by: Dikshita Agarwal <dikshita@codeaurora.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>