msm: vidc: Add configurable option for power collapse in dtsi

Allow configuration of clock gating and power collapse features
separately. Also, rename the incorrectly named clock gating flag from
"has_sw_power_collapse" to "has_gating".

Change-Id: I81f17f9a0d14ba79d51fd67b98545fcaa3e28372
Signed-off-by: Arun Menon <avmenon@codeaurora.org>
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>