staging: sm750fb: Add missing Kconfig dependency

The sm750fb driver has few Framebuffer configuration dependencies that
need to be selected in order to get compiled successfully
Signed-off-by: Hari Prasath Gujulan Elango <hgujulan@visteon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/sm750fb/Kconfig

 config FB_SM750
 	tristate "Silicon Motion SM750 framebuffer support"
 	depends on FB && PCI
+	select FB_MODE_HELPERS
+	select FB_CFB_FILLRECT
+	select FB_CFB_COPYAREA
+	select FB_CFB_IMAGEBLIT
 	help
 	  Frame buffer driver for the Silicon Motion SM750 chip
 	  with 2D accelearion and dual head support.