SCSI: refactor device-matching code in scsi_devinfo.c

In drivers/scsi/scsi_devinfo.c, the scsi_dev_info_list_del_keyed() and
scsi_get_device_flags_keyed() routines contain a large amount of
duplicate code for finding vendor/product matches in a
scsi_dev_info_list.  This patch factors out the duplicate code and
puts it in a separate function, scsi_dev_info_list_find().

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Suggested-by: Giulio Bernardi <ugilio@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>