mtd: mtd->write_user_prot_reg directly

Instead, just call 'mtd_write_user_prot_reg()' and check the '-EOPNOTSUPP' return
code.
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/mtdchar.c

@@ -310,10 +310,6 @@ static ssize_t mtdchar_write(struct file *file, const char __user *buf, size_t c
 			ret = -EROFS;
 			break;
 		case MTD_FILE_MODE_OTP_USER:
-			if (!mtd->write_user_prot_reg) {
-				ret = -EOPNOTSUPP;
-				break;
-			}
 			ret = mtd_write_user_prot_reg(mtd, *ppos, len,
 						      &retlen, kbuf);
 			break;

include/linux/mtd/mtd.h

@@ -381,6 +381,8 @@ static inline int mtd_write_user_prot_reg(struct mtd_info *mtd, loff_t to,
 					  u_char *buf)
 {
 	*retlen = 0;
+	if (!mtd->write_user_prot_reg)
+		return -EOPNOTSUPP;
 	return mtd->write_user_prot_reg(mtd, to, len, retlen, buf);
 }