NetworkPkg: Update IScsiDxe to pass XCODE build

Fix the warning equality comparison with extraneous parentheses
[-Werror,-Wparentheses-equality].

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Liang Vincent <vincent.liang@intel.com>
Reviewed-by: Jiaxin Wu <jiaxin.wu@intel.com>
(cherry picked from commit cf260a47be)

NetworkPkg/IScsiDxe/IScsiDhcp.c

@@ -266,7 +266,7 @@ IScsiDhcpSelectOffer (
     break;
   }
 
-  if ((Index == OptionCount)) {
+  if (Index == OptionCount) {
     Status = EFI_NOT_READY;
   }