staging: atomisp: clean up return logic, remove redunant code

There is no need to check if ret is non-zero, remove this
redundant check and just return the error status from the call
to mt9m114_write_reg_array.

Detected by CoverityScan, CID#1416577 ("Identical code for
different branches")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>