ipq40xx: replace ${} with $()

${} and $() are exactly the same. Follow the convention of using $().

Signed-off-by: Sungbo Eo <mans0n@gorani.run>

target/linux/ipq40xx/image/Makefile

@@ -419,7 +419,7 @@ define Device/linksys_ea6350v3
 	IMAGE_SIZE := 37888k
 	UBINIZE_OPTS := -E 5
 	IMAGES := factory.bin sysupgrade.bin
-	IMAGE/factory.bin := append-kernel | append-uImage-fakehdr filesystem | pad-to $$$${KERNEL_SIZE} | append-ubi | linksys-image type=EA6350v3
+	IMAGE/factory.bin := append-kernel | append-uImage-fakehdr filesystem | pad-to $$$$(KERNEL_SIZE) | append-ubi | linksys-image type=EA6350v3
 	DEVICE_PACKAGES := uboot-envtools
 endef
 TARGET_DEVICES += linksys_ea6350v3
@@ -435,7 +435,7 @@ define Device/linksys_ea8300
 	PAGESIZE := 2048
 	UBINIZE_OPTS := -E 5    # EOD marks to "hide" factory sig at EOF
 	IMAGES := sysupgrade.bin factory.bin
-	IMAGE/factory.bin  := append-kernel | pad-to $$$${KERNEL_SIZE} | append-ubi | linksys-image type=EA8300
+	IMAGE/factory.bin  := append-kernel | pad-to $$$$(KERNEL_SIZE) | append-ubi | linksys-image type=EA8300
 	DEVICE_PACKAGES := uboot-envtools ath10k-firmware-qca9888-ct ipq-wifi-linksys_ea8300 kmod-usb-ledtrig-usbport
 endef
 TARGET_DEVICES += linksys_ea8300
@@ -521,7 +521,7 @@ define Device/qcom_ap-dk01.1-c1
 	IMAGE_SIZE := 26624k
 	$(call Device/FitImage)
 	IMAGES := sysupgrade.bin
-	IMAGE/sysupgrade.bin := append-kernel | pad-to $$$${KERNEL_SIZE} | append-rootfs | pad-rootfs | append-metadata
+	IMAGE/sysupgrade.bin := append-kernel | pad-to $$$$(KERNEL_SIZE) | append-rootfs | pad-rootfs | append-metadata
 endef
 TARGET_DEVICES += qcom_ap-dk01.1-c1