wifi: wext: Remove unused declaration dev_get_wireless_info()

wifi: wext: Remove unused declaration dev_get_wireless_info()

Commit 556829657397 ("[NL80211]: add netlink interface to cfg80211")
declared but never implemented this, remove it.
Commit 11433ee450eb ("[WEXT]: Move to net/wireless") rename net/core/wireless.c
to net/wireless/wext.c, then commit 3d23e349d807 ("wext: refactor") refactor
wext.c to wext-core.c, fix the wext comment.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230807145032.44768-1-yuehaibing@huawei.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>