media: staging: omap4iss: Include asm/cacheflush.h after generic includes

Including asm/cacheflush.h first results in the following build error
when trying to build sparc32:allmodconfig, because 'struct page' has not
been declared, and the function declaration ends up creating a separate
(private) declaration of struct page (as a result of function arguments
being in the scope of the function declaration and definition, not in
global scope).

The C scoping rules do not just affect variable visibility, they also
affect type declaration visibility.

The end result is that when the actual call site is seen in
<linux/highmem.h>, the 'struct page' type in the caller is not the same
'struct page' that the function was declared with, resulting in:

  In file included from arch/sparc/include/asm/page.h:10:0,
                   ...
                   from drivers/staging/media/omap4iss/iss_video.c:15:
  include/linux/highmem.h: In function 'clear_user_highpage':
  include/linux/highmem.h:137:31: error:
	passing argument 1 of 'sparc_flush_page_to_ram' from incompatible
	pointer type

Include generic includes files first to fix the problem.

Fixes: fc96d58c ("[media] v4l: omap4iss: Add support for OMAP4 camera interface - Video devices")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
[ Added explanation of C scope rules - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/staging/media/omap4iss/iss_video.c

@@ -11,7 +11,6 @@
  * (at your option) any later version.
  */
 
-#include <asm/cacheflush.h>
 #include <linux/clk.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
@@ -24,6 +23,8 @@
 #include <media/v4l2-ioctl.h>
 #include <media/v4l2-mc.h>
 
+#include <asm/cacheflush.h>
+
 #include "iss_video.h"
 #include "iss.h"