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/chips/cfi_cmdset_0020.c b/drivers/mtd/chips/cfi_cmdset_0020.c
index 85e8018..3861cca 100644
--- a/drivers/mtd/chips/cfi_cmdset_0020.c
+++ b/drivers/mtd/chips/cfi_cmdset_0020.c
@@ -228,15 +228,15 @@
 		}
 
 	/* Also select the correct geometry setup too */
-	mtd->erase = cfi_staa_erase_varsize;
-	mtd->read = cfi_staa_read;
-        mtd->write = cfi_staa_write_buffers;
-	mtd->writev = cfi_staa_writev;
-	mtd->sync = cfi_staa_sync;
-	mtd->lock = cfi_staa_lock;
-	mtd->unlock = cfi_staa_unlock;
-	mtd->suspend = cfi_staa_suspend;
-	mtd->resume = cfi_staa_resume;
+	mtd->_erase = cfi_staa_erase_varsize;
+	mtd->_read = cfi_staa_read;
+	mtd->_write = cfi_staa_write_buffers;
+	mtd->_writev = cfi_staa_writev;
+	mtd->_sync = cfi_staa_sync;
+	mtd->_lock = cfi_staa_lock;
+	mtd->_unlock = cfi_staa_unlock;
+	mtd->_suspend = cfi_staa_suspend;
+	mtd->_resume = cfi_staa_resume;
 	mtd->flags = MTD_CAP_NORFLASH & ~MTD_BIT_WRITEABLE;
 	mtd->writesize = 8; /* FIXME: Should be 0 for STMicro flashes w/out ECC */
 	mtd->writebufsize = cfi_interleave(cfi) << cfi->cfiq->MaxBufWriteSize;