mtd: add leading underscore to all mtd functions

This patch renames all MTD functions by adding a "_" prefix:

mtd->erase -> mtd->_erase
mtd->read_oob -> mtd->_read_oob
...

The reason is that we are re-working the MTD API and from now on it is
an error to use MTD function pointers directly - we have a corresponding
API call for every pointer. By adding a leading "_" we achieve the following:

1. Make sure we convert every direct pointer users
2. A leading "_" suggests that this interface is internal and it becomes
   less likely that people will use them directly
3. Make sure all the out-of-tree modules stop compiling and the owners
   spot the big API change and amend them.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/nand/alauda.c b/drivers/mtd/nand/alauda.c
index 6a5ff64..ac38f73 100644
--- a/drivers/mtd/nand/alauda.c
+++ b/drivers/mtd/nand/alauda.c
@@ -585,10 +585,10 @@
 	mtd->writesize = 1<<card->pageshift;
 	mtd->type = MTD_NANDFLASH;
 	mtd->flags = MTD_CAP_NANDFLASH;
-	mtd->read = alauda_read;
-	mtd->write = alauda_write;
-	mtd->erase = alauda_erase;
-	mtd->block_isbad = alauda_isbad;
+	mtd->_read = alauda_read;
+	mtd->_write = alauda_write;
+	mtd->_erase = alauda_erase;
+	mtd->_block_isbad = alauda_isbad;
 	mtd->priv = al;
 	mtd->owner = THIS_MODULE;