msm: camera: sensor: Add unified flash driver

pmic and i2c based flash use common driver.
Single driver handles all types of flashes
like i2c based / pmic based / strobe flash
unlike previous driver.

Receives same ioctls from userspace to control
the flash hardware for all types of flashes.

Flash driver is driven from usersapce like
the previous implementation.

Change-Id: Ie6e4aad6056af6ebb7242d7327abf8f003a7bec2
Signed-off-by: Rajesh Bondugula <rajeshb@codeaurora.org>