MLK-20287 drm/imx: ldb: Check retval of sc_misc_set_control in ldb_pixel_link_init

The return value of sc_misc_set_control() should be checked in
ldb_pixel_link_init(), instead of being ignored.  This patch
fixes this issue.

Signed-off-by: Liu Ying <victor.liu@nxp.com>
(cherry picked from commit 7c902e39)