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/maps/uclinux.c b/drivers/mtd/maps/uclinux.c
index 6793074..cfff454 100644
--- a/drivers/mtd/maps/uclinux.c
+++ b/drivers/mtd/maps/uclinux.c
@@ -85,7 +85,7 @@
 	}
 
 	mtd->owner = THIS_MODULE;
-	mtd->point = uclinux_point;
+	mtd->_point = uclinux_point;
 	mtd->priv = mapp;
 
 	uclinux_ram_mtdinfo = mtd;