[MTD] Remove silly MTD_WRITE/READ macros

Most of those macros are unused and the used ones just obfuscate
the code. Remove them and fixup all users.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/drivers/mtd/maps/nettel.c b/drivers/mtd/maps/nettel.c
index 20771b2..0994b5b 100644
--- a/drivers/mtd/maps/nettel.c
+++ b/drivers/mtd/maps/nettel.c
@@ -190,7 +190,7 @@
 		set_current_state(TASK_INTERRUPTIBLE);
 		add_wait_queue(&wait_q, &wait);
 
-		ret = MTD_ERASE(mtd, &nettel_erase);
+		ret = mtd->erase(mtd, &nettel_erase);
 		if (ret) {
 			set_current_state(TASK_RUNNING);
 			remove_wait_queue(&wait_q, &wait);