gl-drm: Remove useless else block

Swap mode is already defaulted to MODE_FULL, so we don't need this
else here.

Signed-off-by: Chris Michael <cp.michael@samsung.com>

src/modules/evas/engines/gl_drm/evas_engine.c

@@ -591,10 +591,6 @@ eng_setup(Evas *eo_e, void *in)
                  (!strcasecmp(s, "4")))
           swap_mode = MODE_QUADRUPLE;
      }
-   else
-     {
-        swap_mode = MODE_FULL;
-     }
 
    /* check for existing engine output */
    if (!epd->engine.data.output)