Fix build warning:
common/lcd.c: In function 'lcd_clear':
common/lcd.c:166:6: warning: variable 'bg_color' set but not used [-Wunused-but-set-variable]
int bg_color;
      ^
common/lcd.c: In function 'lcd_setmem':
common/lcd.c:296:2: warning: format '%d' expects argument of type 'int', but argument 2 has type 'u_long' [-Wformat=]
debug("LCD panel info: %d x %d, %d bit/pix\n", panel_info.vl_col,
  ^
common/lcd.c:296:2: warning: format '%d' expects argument of type 'int', but argument 3 has type 'u_long' [-Wformat=]

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
(cherry picked from commit acfeb43685efb04423ce064c67228d15fa6d3da5)