msm: camera: Fix KW issues in sensor code

Fixing issue where we are dereferencing a NULL pointer.
There is an issue where, if we have a failure in memory
allocation for a mutex, we are not updating rc but freeing
the allocated memory for i2c client. Hence this may lead
to NULL pointer dereference for i2c client at next stage.
Hence we are updating correct rc before freeing the i2c
client memory and returning back to parent function.

CRs-Fixed: 1066972
Change-Id: I7f9493344da2baddb88fd0db14b894fc242d9f9f
Signed-off-by: Tanvi Aggarwal <tanvia@codeaurora.org>