[PATCH] Allow mpage.c to build

When trying to build mpage.c for ARM, I get errors from bio.h since kdev_t
isn't defined.  The following fixes this.

(I fail to see how this can build for anyone as it currently stands; its
probably something x86 specific buried in the asm-i386 includes.)

fs/mpage.c

@@ -12,6 +12,7 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/kdev_t.h>
 #include <linux/bio.h>
 #include <linux/fs.h>
 #include <linux/buffer_head.h>