Minor improvements to the fwdownload code:
o Print the path_id/target we're rescanning so it's not invisible
o No need for XPT_GDEVLIST, all the info is filled in. Remove it

and comment from a mistaken observation. libcam always fills these
in properly.

o Don't leak /dev/xpt fd in success cases.
o Rename fw_rescan_lun to fw_rescan_target and pass sim_mode to

only print path_id and target_id info.

Suggestions by: chs@
Fixes: 9835900cb95bcd068774934961fb1419719d595b
Sponsored by: Netflix