[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/Kconfig b/fs/Kconfig
index 07835d2..475769c 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -1063,33 +1063,18 @@
 	  If reporting bugs, please try to have available a full dump of the
 	  messages at debug level 1 while the misbehaviour was occurring.
 
-config JFFS2_FS_NAND
-	bool "JFFS2 support for NAND flash"
+config JFFS2_FS_WRITEBUFFER
+	bool "JFFS2 write-buffering support"
 	depends on JFFS2_FS
-	default n
+	default y
 	help
-	  This enables the support for NAND flash in JFFS2. NAND is a newer
-	  type of flash chip design than the traditional NOR flash, with
-	  higher density but a handful of characteristics which make it more
-	  interesting for the file system to use.
+	  This enables the write-buffering support in JFFS2.
 
-	  Say 'N' unless you have NAND flash.
-
-config JFFS2_FS_NOR_ECC
-        bool "JFFS2 support for ECC'd NOR flash (EXPERIMENTAL)"
-        depends on JFFS2_FS && EXPERIMENTAL
-        default n
-        help
-          This enables the experimental support for NOR flash with transparent
-          ECC for JFFS2. This type of flash chip is not common, however it is
-          available from ST Microelectronics.
-
-config JFFS2_FS_DATAFLASH
-	bool "JFFS2 support for DataFlash (EXPERIMENTAL)"
-	depends on JFFS2_FS && EXPERIMENTAL
-	default n
-	help
-	  This enables the experimental support for JFFS2 on DataFlash devices.
+	  This functionality is required to support JFFS2 on the following
+	  types of flash devices:
+	    - NAND flash
+	    - NOR flash with transparent ECC
+	    - DataFlash
 
 config JFFS2_COMPRESSION_OPTIONS
 	bool "Advanced compression options for JFFS2"