quantenna_drivers: Pass Module.symvers to kernel build

The Linux kernel build system needs to know the symbol versions of the
symbols that are exported by the Quantenna binary modules. Without
access to the symbol versions, the modpost tool complains about missing
symbol versions.

Change-Id: I4e3782339b36e708bb4ce07a841c59936e425f69
diff --git a/package/quantenna_drivers/quantenna_drivers.mk b/package/quantenna_drivers/quantenna_drivers.mk
index c24891d..c05d59b 100644
--- a/package/quantenna_drivers/quantenna_drivers.mk
+++ b/package/quantenna_drivers/quantenna_drivers.mk
@@ -25,4 +25,8 @@
 	$(QUANTENNA_DRIVERS_MAKE_ENV) $(MAKE) -C $(@D) $(QUANTENNA_DRIVERS_TARGET)_install
 endef
 
+ifeq ($(BR2_PACKAGE_QUANTENNA_DRIVERS),y)
+LINUX_KBUILD_EXTRA_SYMBOLS = $(QUANTENNA_DRIVERS_DIR)/binary_kos.symvers/$(QUANTENNA_DRIVERS_TARGET)/$(LINUX_VERSION_PROBED)/Module.symvers
+endif
+
 $(eval $(call GENTARGETS))