video: fbdev: sm712fb.c: fixed constant-left comparison warning

Fixed a constant-left comparison warning issue check by
scripts/checkpatch.pl:
  WARNING: Comparisons should place the constant on the right side of the test

Signed-off-by: Lynn Lei <lynnl.wit@gmail.com>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Teddy Wang <teddy.wang@siliconmotion.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>