mtd: Stop updating erase_info->state and calling mtd_erase_callback()

MTD users are no longer checking erase_info->state to determine if the
erase operation failed or succeeded. Moreover, mtd_erase_callback() is
now a NOP.

We can safely get rid of all mtd_erase_callback() calls and all
erase_info->state assignments. While at it, get rid of the
erase_info->state field, all MTD_ERASE_XXX definitions and the
mtd_erase_callback() function.

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Bert Kenward <bkenward@solarflare.com>
---
Changes in v2:
- Address a few coding style issues (reported by Miquel)
- Remove comments that are no longer valid (reported by Miquel)
diff --git a/drivers/mtd/lpddr/lpddr2_nvm.c b/drivers/mtd/lpddr/lpddr2_nvm.c
index 2342277..5d73db2a 100644
--- a/drivers/mtd/lpddr/lpddr2_nvm.c
+++ b/drivers/mtd/lpddr/lpddr2_nvm.c
@@ -380,14 +380,8 @@ static int lpddr2_nvm_write(struct mtd_info *mtd, loff_t start_add,
  */
 static int lpddr2_nvm_erase(struct mtd_info *mtd, struct erase_info *instr)
 {
-	int ret = lpddr2_nvm_do_block_op(mtd, instr->addr, instr->len,
-		LPDDR2_NVM_ERASE);
-	if (!ret) {
-		instr->state = MTD_ERASE_DONE;
-		mtd_erase_callback(instr);
-	}
-
-	return ret;
+	return lpddr2_nvm_do_block_op(mtd, instr->addr, instr->len,
+				      LPDDR2_NVM_ERASE);
 }
 
 /*