wifi: ipw: select CRYPTO_LIB_ARC4

wifi: ipw: select CRYPTO_LIB_ARC4

With the WEP/TKIP code having moved to libipw, it now
needs to select CRYPTO_LIB_ARC4 to have the dependency,
and I forgot to move that.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202410111727.FxATs8Yj-lkp@intel.com/
Fixes: 02f220b52670 ("wifi: ipw2x00/lib80211: move remaining lib80211 into libipw")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/20241011115820.070c468b271d.Iac76e81b5cd9a5b949b8c154381128e8131d581d@changeid