radeon: Fix memory leak in radeonCreateScreen2.

Fixes a memory leak defect reported by Coverity.

Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Brian Paul <brianp@vmware.com>

src/mesa/drivers/dri/radeon/radeon_screen.c

@@ -510,8 +510,10 @@ radeonCreateScreen2(__DRIscreen *sPriv)
    }
 
    ret = radeon_set_screen_flags(screen, device_id);
-   if (ret == -1)
+   if (ret == -1) {
+     free(screen);
      return NULL;
+   }
 
    if (getenv("RADEON_NO_TCL"))
 	   screen->chip_flags &= ~RADEON_CHIPSET_TCL;