msm: camera: isp: Enable regulator to turn on clocks in ISPIF.

ISPIF enables VFE clocks to perform a hardware reset. VFE clocks
needs VFE regulators to be enabled to turn on clocks. This change
enables the regulators before the clocks are enabled and disables
regulators after clocks are disabled.

Change-Id: I8a65f8238cfbdaac64184e697e3f7e2a5665d4e9
Signed-off-by: Sreesudhan Ramakrish Ramkumar <srramku@codeaurora.org>