mac80211: rescan the package metadata when a driver .mk file changes

The kmod definitions live in ath.mk, intel.mk and the other included
.mk files, but the package scan only regenerates the mac80211 metadata
when the Makefile changes. An edit to a DEPENDS or Kconfig line in
ath.mk is then ignored until tmp/ is deleted by hand.

Name the included files in SCAN_DEPS, as linux-firmware does.

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Julius Bairaktaris <julius@bairaktaris.de>
Link: https://github.com/openwrt/openwrt/pull/25953
Signed-off-by: Robert Marko <robimarko@gmail.com>

package/kernel/mac80211/Makefile

@@ -41,6 +41,8 @@ PKG_CONFIG_DEPENDS:= \
 	CONFIG_PACKAGE_IWLWIFI_DEBUGFS \
 	CONFIG_PACKAGE_RTLWIFI_DEBUG \
 
+SCAN_DEPS = *.mk
+
 include $(INCLUDE_DIR)/package.mk
 
 WMENU:=Wireless Drivers