PXE driver bug fix.

PXE driver bug fix.

1. Update the parameter check of PXE.UdpRead() to align with spec definition.
2. Update PXE driver to use EFI_PXE_BASE_CODE_UDP_OPFLAGS_ANY_DEST_IP when calling UdpRead to receive server discovery message.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17075 6f19259b-4bc3-4df7-8a09-765794883524