Revert "bcm53xx: remove useless echo in 02_network"

This reverts commit b1f6a5d9dffd8da30800e9e66ea772554bbba778.

In this particular case, the echo command was _not_ useless, but
converted the newlines back to spaces.

Add a comment into the code to make that obvious for the next one
looking at it like me.

Signed-off-by: Adrian Schmutzler <[email protected]>

target/linux/bcm53xx/base-files/etc/board.d/02_network

@@ -55,8 +55,9 @@ bcm53xx_setup_interfaces()
 		# vlan2ports=4 5u
 		# and early Netgear R8000 was using
 		# vlan1ports=3 2 1 0 5 7 8*
-		vlan1ports="$(nvram get vlan1ports | tr " " "\n" | sort)"
-		vlan2ports="$(nvram get vlan2ports | tr " " "\n" | sort)"
+		# (the enclosing echo is needed to convert newline back to space)
+		vlan1ports="$(echo $(nvram get vlan1ports | tr " " "\n" | sort))"
+		vlan2ports="$(echo $(nvram get vlan2ports | tr " " "\n" | sort))"
 		if echo "$vlan1ports" | egrep -q "^1 2 3 4 5" && \
 		   echo "$vlan2ports" | egrep -q "^0 5"; then
 			ucidef_add_switch "switch0" \