mtd: fix different address space noise

In mtd_ioctl MEMGETREGIONINFO the region_user_info pointer ur
is cast in __kernel space. This produces a number of sparse warnings
like:

warning: cast removes address space of expression
warning: incorrect type in initializer (different address spaces)
   expected unsigned int const [noderef] <asn:1>*register __p
   got unsigned int *<noident>

Since argp is already a void __user * just use it dirrectly without
the cast and make ur a __user *.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/mtdchar.c

@@ -482,7 +482,7 @@ static int mtd_ioctl(struct inode *inode, struct file *file,
 	{
 		uint32_t ur_idx;
 		struct mtd_erase_region_info *kr;
-		struct region_info_user *ur = (struct region_info_user *) argp;
+		struct region_info_user __user *ur = argp;
 
 		if (get_user(ur_idx, &(ur->regionindex)))
 			return -EFAULT;