Changed sys_mknod() prototype to have unsigned int passed to it
instead of current dev_t.  Added old_decode_dev() in sys_mknod() and
made sure that its callers are passing it old_encode_dev(<value>)
	Switched sys_ustat() and its variants from dev_t to unsigned (and
added old_decode_dev()).
	Took care of assignments to ROOT_DEV - again, old_decode_dev().
	Late-boot search in devfs (call sys_newstat() and compare with
st_rdev) also updated.