[MTD] Restore MTD_ROM and MTD_RAM types

Let's not attempt the abolition of mtd->type until/unless it's properly
thought through. And certainly, let's not do it by halves.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/mtd/devices/phram.c

@@ -149,7 +149,7 @@ static int register_device(char *name, unsigned long start, unsigned long len)
 	new->mtd.read = phram_read;
 	new->mtd.write = phram_write;
 	new->mtd.owner = THIS_MODULE;
-	new->mtd.type = MTD_GENERIC_TYPE;
+	new->mtd.type = MTD_RAM;
 	new->mtd.erasesize = PAGE_SIZE;
 
 	ret = -EAGAIN;