PCI: cleanup MSI code

Cleanup MSI code as follows:

 - fix some types
 - fix strange local variable definition
 - delete unnecessary blank line
 - add comment to #endif which is far from corresponding #ifdef

Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>