ipw2200: remove redundant check of rc < 0

The check for rc < 0 is always false so the check is redundant
and can be removed.

Detected with CoverityScan, CID#101143 ("Logically dead code")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>