[i2c] [PATCH -mm] i2c-at91: compile fix (IS_ERR)

[Alexey Dobriyan]

  CC      drivers/i2c/busses/i2c-at91.o
drivers/i2c/busses/i2c-at91.c: In function 'at91_i2c_probe':
drivers/i2c/busses/i2c-at91.c:213: warning: implicit declaration of function 'IS_ERR'

Signed-off-by: Alexey Dobriyan <adobriyan at gmail.com>
---

 drivers/i2c/busses/i2c-at91.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/i2c/busses/i2c-at91.c
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -16,6 +16,7 @@
 #include <linux/module.h>
 #include <linux/version.h>
 #include <linux/kernel.h>
+#include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/delay.h>