fbdev: fix omap2/omapfb/dss/ indentation warning

Fix indentation warning (from gcc 8.1.0) in omap2/omapfb:

../drivers/video/fbdev/omap2/omapfb/dss/dispc.c: In function 'pixinc':
../drivers/video/fbdev/omap2/omapfb/dss/dispc.c:1859:2: warning: this 'else' clause does not guard... [-Wmisleading-indentation]
  else
  ^~~~
../drivers/video/fbdev/omap2/omapfb/dss/dispc.c:1861:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
   return 0;
   ^~~~~~
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>