msm: camera: Use utility function for i2c write

Use common utility function for i2c writes in flash interface.
If all i2c transfers are routed through common utility function,
only the utility function implemention will change if i2c inteface
changes across platform.

Change-Id: If42f6ec274e42a61b7406031d87b6908525d9442
Signed-off-by: Sreesudhan Ramakrish Ramkumar <srramku@codeaurora.org>