[MTD] replace MTD_RAM with MTD_GENERIC_TYPE

Ram devices get the extra capability of MTD_NO_ERASE - not requiring
an explicit erase before writing to it.  Currently only mtdblock uses
this capability.  Rest of the patch is a simple text replacement.

Signed-off-by: Joern Engel <joern@wh.fh-wedel.de>
diff --git a/include/mtd/mtd-abi.h b/include/mtd/mtd-abi.h
index 1ce365b..7ccadb1 100644
--- a/include/mtd/mtd-abi.h
+++ b/include/mtd/mtd-abi.h
@@ -24,7 +24,6 @@
 };
 
 #define MTD_ABSENT		0
-#define MTD_RAM			1
 #define MTD_NORFLASH		3
 #define MTD_NANDFLASH		4
 #define MTD_DATAFLASH		6
@@ -32,10 +31,11 @@
 
 #define MTD_WRITEABLE		0x400	/* Device is writeable */
 #define MTD_BIT_WRITEABLE	0x800	/* Single bits can be flipped */
+#define MTD_NO_ERASE		0x1000	/* No erase necessary */
 
 // Some common devices / combinations of capabilities
 #define MTD_CAP_ROM		0
-#define MTD_CAP_RAM		(MTD_WRITEABLE | MTD_BIT_WRITEABLE)
+#define MTD_CAP_RAM		(MTD_WRITEABLE | MTD_BIT_WRITEABLE | MTD_NO_ERASE)
 #define MTD_CAP_NORFLASH	(MTD_WRITEABLE | MTD_BIT_WRITEABLE)
 #define MTD_CAP_NANDFLASH	(MTD_WRITEABLE)