[JFFS2] Use a single config option for write buffer support

This patch replaces the current CONFIG_JFFS2_FS_NAND, CONFIG_JFFS2_FS_NOR_ECC
and CONFIG_JFFS2_FS_DATAFLASH with a single configuration option -
CONFIG_JFFS2_FS_WRITEBUFFER.

The only functional change of this patch is that the slower div/mod
calculations for SECTOR_ADDR(), PAGE_DIV() and PAGE_MOD() are now always
used when CONFIG_JFFS2_FS_WRITEBUFFER is enabled.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c
index 5b7c960..c91c66e 100644
--- a/fs/jffs2/fs.c
+++ b/fs/jffs2/fs.c
@@ -7,7 +7,7 @@
  *
  * For licensing information, see the file 'LICENCE' in this directory.
  *
- * $Id: fs.c,v 1.52 2005/02/09 09:17:40 pavlov Exp $
+ * $Id: fs.c,v 1.53 2005/02/09 09:23:53 pavlov Exp $
  *
  */
 
@@ -450,13 +450,11 @@
 
 	c = JFFS2_SB_INFO(sb);
 
-#ifndef CONFIG_JFFS2_FS_NAND
+#ifndef CONFIG_JFFS2_FS_WRITEBUFFER
 	if (c->mtd->type == MTD_NANDFLASH) {
 		printk(KERN_ERR "jffs2: Cannot operate on NAND flash unless jffs2 NAND support is compiled in.\n");
 		return -EINVAL;
 	}
-#endif
-#ifndef CONFIG_JFFS2_FS_DATAFLASH
 	if (c->mtd->type == MTD_DATAFLASH) {
 		printk(KERN_ERR "jffs2: Cannot operate on DataFlash unless jffs2 DataFlash support is compiled in.\n");
 		return -EINVAL;