s390/cio: remove unused include linux/spinlock.h from cio.h

* The linux/spinlock.h header was included indirectly by the decompressor
  and brought unnecessary build dependencies.
* Use proper includes in files which either directly or indirectly included
  cio.h and were hidden until now by the included linux/spinlock.h, e.g.
  linux/string.h for memcpy() or asm/page.h for PAGE_SIZE.

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>