staging: sm750fb: remove redundant pointer 'output'

Pointer 'output' is being assigned but is never used hence it is redundant
and can be removed.

Cleans up clang warning:
warning: variable 'output' set but not used [-Wunused-but-set-variable]
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/sm750fb/sm750.c

@@ -512,12 +512,10 @@ static int lynxfb_ops_check_var(struct fb_var_screeninfo *var,
 {
 	struct lynxfb_par *par;
 	struct lynxfb_crtc *crtc;
-	struct lynxfb_output *output;
 	resource_size_t request;
 
 	par = info->par;
 	crtc = &par->crtc;
-	output = &par->output;
 
 	pr_debug("check var:%dx%d-%d\n",
 		 var->xres,