staging: xgifb: Compress return logic into one line.

Simplify return logic to avoid unnecessary variable assignments.

Coccinelle was used with this semantic patch:
@@
local idexpression ret;
expression e;
@@

-ret =
+return
     e;
-return ret;

Signed-off-by: Elise Lennion <elise.lennion@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>