[MTD] Use single flag to mark writeable devices.

Two flags exist to decide whether a device is writeable or not.  None of
those two flags is checked for independently, so they are clearly redundant,
if not an invitation to bugs.  This patch removed both of them, replacing
them with a single new flag.
Signed-off-by: Joern Engel <joern@wh.fh-wedel.de>

include/mtd/mtd-abi.h

@@ -30,17 +30,15 @@ struct mtd_oob_buf {
 #define MTD_NANDFLASH		4
 #define MTD_DATAFLASH		6
 
-#define MTD_CLEAR_BITS		1       // Bits can be cleared (flash)
-#define MTD_SET_BITS		2       // Bits can be set
 #define MTD_ECC			128	// Device capable of automatic ECC
 #define MTD_PROGRAM_REGIONS	512	// Configurable Programming Regions
+#define MTD_WRITEABLE		0x400	/* Device is writeable */
 
 // Some common devices / combinations of capabilities
 #define MTD_CAP_ROM		0
-#define MTD_CAP_RAM		(MTD_CLEAR_BITS|MTD_SET_BITS)
-#define MTD_CAP_NORFLASH	(MTD_CLEAR_BITS)
-#define MTD_CAP_NANDFLASH	(MTD_CLEAR_BITS)
-#define MTD_WRITEABLE		(MTD_CLEAR_BITS|MTD_SET_BITS)
+#define MTD_CAP_RAM		(MTD_WRITEABLE)
+#define MTD_CAP_NORFLASH	(MTD_WRITEABLE)
+#define MTD_CAP_NANDFLASH	(MTD_WRITEABLE)
 
 
 // Types of automatic ECC/Checksum available