fix SystemRescue 11.02 boot

[jcpvdm]

Fix #2958

Cause: xzcat is failing on ventoy_unpack_initramfs() when $vtskip != 0:

Ventoy/IMG/cpio/ventoy/init_chain

Lines 93 to 95 in b11c387

	else
	dd if=$vtfile skip=$vtskip iflag=skip_bytes status=none | ${vtx:5} | (cpio -idmu 2>>$VTLOG; cat > $vttmp)
	fi

It's not attempting xzminidec and xzcat_musl, unlike the case where $vtskip == 0,

Ventoy/IMG/cpio/ventoy/init_chain

Lines 76 to 89 in b11c387

	if [ $vtskip -eq 0 ]; then
	if [ "${vtx:5}" = "xzcat" ]; then
	rm -f $VTOY_PATH/xzlog
	${vtx:5} $vtfile 2> $VTOY_PATH/xzlog | (cpio -idmu 2>>$VTLOG; cat > $vttmp)
	if grep -q 'corrupted data' $VTOY_PATH/xzlog; then
	echo 'xzcat failed, now try xzminidec...' >> $VTLOG
	rm -f $VTOY_PATH/xzlog
	cat $vtfile | xzminidec 2> $VTOY_PATH/xzlog | (cpio -idmu 2>>$VTLOG; cat > $vttmp)
	if grep -q 'limit' $VTOY_PATH/xzlog; then
	echo 'xzminidec failed, now try xzcat_musl ...' >> $VTLOG
	xzcat_musl $vtfile | (cpio -idmu 2>>$VTLOG; cat > $vttmp)
	fi
	fi