video: smscufx: Return an error code only as a constant in ufx_realloc_framebuffer()

* Return an error code without storing it in an intermediate variable.

* Delete the label "error" and local variable "retval"
  which became unnecessary with this refactoring.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Cc: Steve Glendinning <steve.glendinning@shawell.net>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>