[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/include/linux/jffs2_fs_sb.h b/include/linux/jffs2_fs_sb.h
index faec295..1bd6cdf 100644
--- a/include/linux/jffs2_fs_sb.h
+++ b/include/linux/jffs2_fs_sb.h
@@ -1,4 +1,4 @@
-/* $Id: jffs2_fs_sb.h,v 1.49 2005/02/09 09:17:41 pavlov Exp $ */
+/* $Id: jffs2_fs_sb.h,v 1.50 2005/02/09 09:23:55 pavlov Exp $ */
 
 #ifndef _JFFS2_FS_SB
 #define _JFFS2_FS_SB
@@ -94,7 +94,7 @@
 	   to an obsoleted node. I don't like this. Alternatives welcomed. */
 	struct semaphore erase_free_sem;
 
-#if defined CONFIG_JFFS2_FS_NAND || defined CONFIG_JFFS2_FS_NOR_ECC || defined CONFIG_JFFS2_FS_DATAFLASH
+#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
 	/* Write-behind buffer for NAND flash */
 	unsigned char *wbuf;
 	uint32_t wbuf_ofs;