arm: mxs: include asm/processor.h for cpu_relax()

I get this build error as of today:

arch/arm/mach-mxs/ocotp.c: In function 'mxs_get_ocotp':
arch/arm/mach-mxs/ocotp.c:54: error: implicit declaration of function 'cpu_relax'
make[2]: *** [arch/arm/mach-mxs/ocotp.o] Error 1

Looks like it has been indirectly included before which broke now.
Include it directly.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-mxs/ocotp.c

@@ -16,6 +16,8 @@
 #include <linux/err.h>
 #include <linux/mutex.h>
 
+#include <asm/processor.h>	/* for cpu_relax() */
+
 #include <mach/mxs.h>
 
 #define OCOTP_WORD_OFFSET		0x20