`boot.d/70.dhclient.conf`: Appends management interface entry at each boot

[paulmenzel]

dentOS/packages/base/all/vendor-config-onl/src/boot.d/70.dhclient.conf

Lines 10 to 12 in 75b3bd5

	echo "interface \"ma1\" {" >> $DHCLIENT_CONF
	echo " send dhcp-client-identifier 01:$MA1_MAC;" >> $DHCLIENT_CONF
	echo "}" >> $DHCLIENT_CONF

The >> causes the entry to be written at each boot.

\cc @buczek

[paulmenzel]

Commit opencomputeproject/OpenNetworkLinux@7714680 from August 2016 to solve the issue DHCP req between ONIE and ONL, and @Lewis-Kang commented the same issue there.

[gavin-Angry-Birds]

I will look into making this boot script idempotent.

The ma1 dhcp-client-identifier block should remain (ONIE/ONLcompatibility). I plan to skip appending when the ma1 interface
block is already present in dhclient.conf.

I do not have DENT switch hardware; I will verify with a temp DHCLIENT_CONF / MA1_MAC and describe that in the PR.