mac80211: Do not build b43legacy on BRCM47xx mips74 subtarget

b43legacy needs ssb support and we do not compile the mips74 subtarget
of the brcm47xx target with SSB support. This causes a build failure in
the mac80211 package and only some of the kernel modules are being
created.

I am not aware of any device with a BRCM47xx mips74 CPU which uses a
b43legacy compatible device.

Fixes: FS#2334
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
(cherry picked from commit e05310b9b80f944c718374b449b6fe48d06d412d)

package/kernel/mac80211/broadcom.mk

@@ -347,7 +347,7 @@ define KernelPackage/b43legacy
   URL:=https://wireless.wiki.kernel.org/en/users/drivers/b43
   KCONFIG:= \
   	CONFIG_HW_RANDOM=y
-  DEPENDS+= +kmod-mac80211 +!(TARGET_brcm47xx||TARGET_brcm63xx):kmod-ssb +b43legacy-firmware
+  DEPENDS+= +kmod-mac80211 +!(TARGET_brcm47xx||TARGET_brcm63xx):kmod-ssb @!TARGET_brcm47xx_mips74k +b43legacy-firmware
   FILES:=$(PKG_BUILD_DIR)/drivers/net/wireless/broadcom/b43legacy/b43legacy.ko
   AUTOLOAD:=$(call AutoProbe,b43legacy)
   MENU:=1