OMAPDSS: add missing sizes.h includes

When compiling on x86, we get compilation errors for dss.c and dispc.c:

drivers/video/omap2/dss/dispc.c:126:11: error: ‘SZ_4K’ undeclared here
(not in a function)

include <linux/sizes.h> to fix compilation.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/dispc.c

@@ -36,6 +36,7 @@
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/sizes.h>
 
 #include <video/omapdss.h>
 

drivers/video/omap2/dss/dss.c

@@ -32,6 +32,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/gfp.h>
+#include <linux/sizes.h>
 
 #include <video/omapdss.h>