mn10300: remove wrapper header for asm/device.h

mn10300's asm/device.h is merely including asm-generic/device.h.  Thus,
the arch specific header can be omitted and the generic header can be
used directly.

Link: http://lkml.kernel.org/r/20170517124857.26834-1-tklauser@distanz.ch


Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>