cfg80211: ignore supported rates for nonexistant bands on scan

Fixes wpa_supplicant p2p_find on 5GHz-only devices

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Git-commit: 1b09cd82d8c479700ef6185665839d1020b02519
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Change-Id: Icadd03bfff17c5fd8da3e15e7b69b42a730e0ef0
Signed-off-by: Ahmad Kholaif <akholaif@codeaurora.org>