ath10k: remove hard dependency on ath10k-firmware-qca988x

We use our own firmware package.

patches/openwrt/0006-ath10k-firmware-add-Candela-Technologies-firmware-for-QCA988X.patch

@@ -57,3 +57,16 @@ index b03d644..7d4d449 100644
 +$(eval $(call BuildPackage,ath10k-firmware-qca988x-ct))
  $(eval $(call BuildPackage,ath10k-firmware-qca99x0))
  $(eval $(call BuildPackage,ath10k-firmware-qca6174))
+diff --git a/package/kernel/mac80211/Makefile b/package/kernel/mac80211/Makefile
+index 30da1cf..cd8d670 100644
+--- a/package/kernel/mac80211/Makefile
++++ b/package/kernel/mac80211/Makefile
+@@ -247,7 +247,7 @@ define KernelPackage/ath10k
+   $(call KernelPackage/mac80211/Default)
+   TITLE:=Atheros 802.11ac wireless cards support
+   URL:=https://wireless.wiki.kernel.org/en/users/Drivers/ath10k
+-  DEPENDS+= @PCI_SUPPORT +kmod-ath +@DRIVER_11N_SUPPORT +@DRIVER_11W_SUPPORT +@KERNEL_RELAY +ath10k-firmware-qca988x
++  DEPENDS+= @PCI_SUPPORT +kmod-ath +@DRIVER_11N_SUPPORT +@DRIVER_11W_SUPPORT +@KERNEL_RELAY
+   FILES:= \
+ 	$(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath10k/ath10k_core.ko \
+ 	$(PKG_BUILD_DIR)/drivers/net/wireless/ath/ath10k/ath10k_pci.ko