[media] staging/media: lirc_imon: add a __user annotation

This silences the following Sparse warnings:
lirc_imon.c:404:32: warning: incorrect type in argument 1 (different address spaces)
lirc_imon.c:404:32:    expected void const [noderef] <asn:1>*<noident>
lirc_imon.c:404:32:    got char const *buf
lirc_imon.c:117:28: warning: incorrect type in initializer (incompatible argument 2 (different address spaces))
lirc_imon.c:117:28:    expected long ( *write )( ... )
lirc_imon.c:117:28:    got long ( static [toplevel] *<noident> )( ... )

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/media/lirc/lirc_imon.c

@@ -63,7 +63,7 @@ static int display_open(struct inode *inode, struct file *file);
 static int display_close(struct inode *inode, struct file *file);
 
 /* VFD write operation */
-static ssize_t vfd_write(struct file *file, const char *buf,
+static ssize_t vfd_write(struct file *file, const char __user *buf,
 			 size_t n_bytes, loff_t *pos);
 
 /* LIRC driver function prototypes */
@@ -369,7 +369,7 @@ static int send_packet(struct imon_context *context)
  * than 32 bytes are provided spaces will be appended to
  * generate a full screen.
  */
-static ssize_t vfd_write(struct file *file, const char *buf,
+static ssize_t vfd_write(struct file *file, const char __user *buf,
 			 size_t n_bytes, loff_t *pos)
 {
 	int i;