Notify IpClient DHCP process success before configuring Interface.

This patch fixes the bug introduced by aosp/1169224 which moves
notifySuccess function to DhcpBoundState#enter. This behavior
is correct for DHCP reacquiring process (e.g. when client renews
or rebinds the previous leased IPv4 address, then enters Bound
state after receiving DHCPACK packet). However, this is incorrect
for DHCP solicit at the first time, since notifying IpClient DHCP
success after configuring interface causes mDhcpResult member is
still empty when handleLinkPropertiesUpdate is triggered by netd
completes configuring interface with new IPv4 address. Hence, new
Link Properties passed to wifi state machine doesn't contain the
available DNS servers received from DHCPACK.

Moving notifySuccess before sending CMD_CONFIGURE_LINKADDRESS cmd
to IpClient ensures mDhcpResult member has been initialize correctly
before assembling new LinkProperties.

Bug:146850745
Test: atest NetworkStackIntegrationTests NetworkStackTests
Change-Id: Ifb990ccc06c1374e616f71038b1811640821e954