V4L: saa7146: Fix allocation of clipping memory

Olaf Hering pointed out that SAA7146_CLIPPING_MEM would become
very large for PAGE_SIZE > 4K.

In fact, the number of clipping windows is limited to 16,
and calculate_clipping_registers_rect() does not use more
than 256 bytes. SAA7146_CLIPPING_MEM adjusted accordingly.

(cherry picked from commit 7a7cd19209)

Thanks-to: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

include/media/saa7146_vv.h

@@ -238,7 +238,8 @@ void saa7146_res_free(struct saa7146_fh *fh, unsigned int bits);
 #define SAA7146_HPS_SYNC_PORT_B		0x01
 
 /* some memory sizes */
-#define SAA7146_CLIPPING_MEM	(14*PAGE_SIZE)
+/* max. 16 clipping rectangles */
+#define SAA7146_CLIPPING_MEM	(16 * 4 * sizeof(u32))
 
 /* some defines for the various clipping-modes */
 #define SAA7146_CLIPPING_RECT		0x4