qualcommbe: ipq95xx: Set target as source-only

Set target as source-only for now as only the Reference Board is
supported and needs to better evaluated with real Devices.

Link: openwrt#17725
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

target/linux/qualcommbe/Makefile

@@ -3,7 +3,7 @@ include $(TOPDIR)/rules.mk
 ARCH:=aarch64
 BOARD:=qualcommbe
 BOARDNAME:=Qualcomm Atheros 802.11be WiSoC-s
-FEATURES:=squashfs ramdisk fpu nand rtc emmc
+FEATURES:=squashfs ramdisk fpu nand rtc emmc source-only
 KERNELNAME:=Image
 CPU_TYPE:=cortex-a53
 SUBTARGETS:=ipq95xx