ipq806x: onhub: Enable fstools_partname_fallback_scan

When fstools is unable to parse our root=<...> arg correctly, it can
fall back to scanning all block devices for a 'rootfs_data' partition.
This fallback was deemed wrong (or at least, a breaking/incompatible
change) for some targets, so we're forced to opt back into it with
fstools_partname_fallback_scan=1.

Without this, OnHub devices will use a rootfs-appended loop device for
rootfs_data instead of the intended 3rd partition.

While I'm at it, just move all the boot args into the 'cros-vboot'
build rule, instead of using the custom bootargs-append. All cros-vboot
subtargets here are using the same rootwait (to support both eMMC and
USB boot) and root/partition args.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
[ drop unrelated comments in commit description ]
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

target/linux/ipq806x/files-5.15/arch/arm/boot/dts/qcom-ipq8064-asus-onhub.dts

@@ -11,10 +11,6 @@
 / {
 	model = "ASUS OnHub";
 	compatible = "asus,onhub", "google,arkham", "qcom,ipq8064";
-
-	chosen {
-		bootargs-append = " rootwait";
-	};
 };
 
 &qcom_pinmux {

target/linux/ipq806x/files-5.15/arch/arm/boot/dts/qcom-ipq8064-tplink-onhub.dts

@@ -11,10 +11,6 @@
 / {
 	model = "TP-Link OnHub";
 	compatible = "tplink,onhub", "google,whirlwind-sp5", "qcom,ipq8064";
-
-	chosen {
-		bootargs-append = " rootwait";
-	};
 };
 
 &qcom_pinmux {

target/linux/ipq806x/image/chromium.mk

@@ -20,7 +20,9 @@ endef
 # (PARTNROFF=1) partition as their rootfs.
 define Build/cros-vboot
 	$(STAGING_DIR_HOST)/bin/cros-vbutil \
-		-k $@ -c "root=PARTUUID=%U/PARTNROFF=1" -o $@.new
+		-k $@ \
+		-c "root=PARTUUID=%U/PARTNROFF=1 rootwait fstools_partname_fallback_scan=1" \
+		-o $@.new
 	@mv $@.new $@
 endef