mtd: remove R/O checking duplication

Many drivers check whether the partition is R/O and return -EROFS if yes.
Let's stop having duplicated checks and move them to the API functions
instead.

And again a bit of noise - deleted few too sparse newlines, sorry.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index fbe2c8a..33d32c6 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -172,8 +172,6 @@
 		size_t *retlen, const u_char *buf)
 {
 	struct mtd_part *part = PART(mtd);
-	if (!(mtd->flags & MTD_WRITEABLE))
-		return -EROFS;
 	return mtd_write(part->master, to + part->offset, len, retlen, buf);
 }
 
@@ -181,8 +179,6 @@
 		size_t *retlen, const u_char *buf)
 {
 	struct mtd_part *part = PART(mtd);
-	if (!(mtd->flags & MTD_WRITEABLE))
-		return -EROFS;
 	return mtd_panic_write(part->master, to + part->offset, len, retlen,
 			       buf);
 }
@@ -192,9 +188,6 @@
 {
 	struct mtd_part *part = PART(mtd);
 
-	if (!(mtd->flags & MTD_WRITEABLE))
-		return -EROFS;
-
 	if (to >= mtd->size)
 		return -EINVAL;
 	if (ops->datbuf && to + ops->len > mtd->size)
@@ -220,8 +213,6 @@
 		unsigned long count, loff_t to, size_t *retlen)
 {
 	struct mtd_part *part = PART(mtd);
-	if (!(mtd->flags & MTD_WRITEABLE))
-		return -EROFS;
 	return mtd_writev(part->master, vecs, count, to + part->offset,
 			  retlen);
 }
@@ -230,8 +221,7 @@
 {
 	struct mtd_part *part = PART(mtd);
 	int ret;
-	if (!(mtd->flags & MTD_WRITEABLE))
-		return -EROFS;
+
 	instr->addr += part->offset;
 	ret = mtd_erase(part->master, instr);
 	if (ret) {
@@ -304,8 +294,6 @@
 	struct mtd_part *part = PART(mtd);
 	int res;
 
-	if (!(mtd->flags & MTD_WRITEABLE))
-		return -EROFS;
 	ofs += part->offset;
 	res = mtd_block_markbad(part->master, ofs);
 	if (!res)