tests: Explicitly store hex IPv6 PD prefix.

While the dynamic extraction with awk and sed is nifty, we do know
ahead of time what the prefix will be, so let's just keep it
simple.

In a subsequent patch we will use an IPv6 prefix with leading zero
which will break the current approach.

Signed-off-by: Frode Nordahl <fnordahl@ubuntu.com>
Signed-off-by: Dumitru Ceara <dceara@redhat.com>

tests/system-common-macros.at

@@ -473,13 +473,13 @@ AT_CHECK([ovn-nbctl get logical_router_port rp-sw0 ipv6_prefix | cut -c3-16], [0
 [2001:1db8:3333]
 ])
 
-prefix=$(ovn-nbctl list logical_router_port rp-public | awk -F/ '/ipv6_prefix/{print substr($ 1,25,9)}' | sed 's/://g')
+hex_prefix=0x20011db8
 ovn-nbctl list logical_router_port rp-public > /tmp/rp-public
 
 # Wait for 2 renew on each port.
-NETNS_START_TCPDUMP([server], [-c 4 -nni s1 ip6[[48:1]]=0x05 and ip6[[113:4]]=0x${prefix}], [renew])
+NETNS_START_TCPDUMP([server], [-c 4 -nni s1 ip6[[48:1]]=0x05 and ip6[[113:4]]=${hex_prefix}], [renew])
 # Reply message with Status OK
-NETNS_START_TCPDUMP([server], [-c 4 -nni s1 ip6[[48:1]]=0x07 and ip6[[81:4]]=0x${prefix}], [reply])
+NETNS_START_TCPDUMP([server], [-c 4 -nni s1 ip6[[48:1]]=0x07 and ip6[[81:4]]=${hex_prefix}], [reply])
 
 OVS_WAIT_UNTIL([
     total_pkts=$(cat renew.tcpdump | wc -l)
@@ -495,7 +495,7 @@ check ovn-nbctl set logical_router_port rp-public options:prefix=false
 check ovn-nbctl set logical_router_port rp-sw0 options:prefix=false
 check ovn-nbctl --wait=hv set logical_router_port rp-sw1 options:prefix=true
 sleep_sb
-NETNS_START_TCPDUMP([server], [-c 2 -nni s1 ip6[[48:1]]=0x05 and ip6[[113:4]]=0x${prefix}], [renew2])
+NETNS_START_TCPDUMP([server], [-c 2 -nni s1 ip6[[48:1]]=0x05 and ip6[[113:4]]=${hex_prefix}], [renew2])
 
 # Sleep enough to have solicit and renew being sent, then wait for 2 renew.
 # The reply to the request will usually be received as sb is sleeping.