mn10300: use for_each_pci_dev to simplify the code

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>