MdeModulePkg: IP4 should re-initiate a DHCP if it detects network reconnection

v2:
* Update the MediaPresent detect declaring.

IP4 driver should re-initiate a DHCP if it detects that there is a network.
To fix this issue, we can implement the DHCP re-initiate policy while the media
change detected. The Ip4 driver should set a timer to signal the Ip4 to run the
DHCP configuration again(D.O.R.A). IP4 driver should free old IP address related
resource, then initiate a DHCP process to acquire new IP.

Cc: Ye Ting <ting.ye@intel.com>
Cc: Zhang Lubo <lubo.zhang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiaxin Wu <jiaxin.wu@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
Reviewed-by: Lubo Zhang <lubo.zhang@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18232 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Universal/Network/Ip4Dxe/Ip4Config2Impl.c

@@ -492,6 +492,7 @@ Ip4Config2SetDefaultAddr (
   ASSERT (IpIf != NULL);
 
   if ((IpIf->Ip == StationAddress) && (IpIf->SubnetMask == SubnetMask)) {
+    IpSb->State = IP4_SERVICE_CONFIGED;
     return EFI_SUCCESS;
   }