video: fbdev: uvesafb: Fix set but not used warning

Fix W=1 warning by deleting unused local variable.

v2:
- Updated subject (Lee)

v3:
- Return early in case of an error (Thomas)

Signed-off-by: Sam Ravnborg <[e-mail]>
Acked-by: Thomas Zimmermann <[e-mail]>
Cc: Michal Januszewski <[e-mail]>
Cc: [e-mail]
Cc: Lee Jones <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/video/fbdev/uvesafb.c

···
 	task->t.regs.eax = 0x4f0a;
 	task->t.regs.ebx = 0x0;
 	err = uvesafb_exec(task);
+	if (err)
+		return err;
 
 	if ((task->t.regs.eax & 0xffff) != 0x4f || task->t.regs.es < 0xc000) {
 		par->pmi_setpal = par->ypan = 0;