NetworkPkg IScsiDxe: Fix build error for lastest VS2015 compiler

The IScsiDxe module encounters a build error for IA32 arch using the
latest version of VS2015:

IScsiDxe.lib(IScsiProto.obj) : error LNK2001: unresolved external symbol
__allmul

The cause is line 141 in file NetworkPkg\IScsiDxe\IScsiProto.c. The third
parameter for gBS->SetTimer() function is of type UINT64, so the
multiplication should use the MultU64x32() function now.

Cc: Siyuan Fu <siyuan.fu@intel.com>
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
diff --git a/NetworkPkg/IScsiDxe/IScsiProto.c b/NetworkPkg/IScsiDxe/IScsiProto.c
index c82290e..5092365 100644
--- a/NetworkPkg/IScsiDxe/IScsiProto.c
+++ b/NetworkPkg/IScsiDxe/IScsiProto.c
@@ -138,7 +138,11 @@
   //

   // Start the timer, and wait Timeout seconds to establish the TCP connection.

   //

-  Status = gBS->SetTimer (Conn->TimeoutEvent, TimerRelative, Timeout * TICKS_PER_MS);

+  Status = gBS->SetTimer (

+                  Conn->TimeoutEvent,

+                  TimerRelative,

+                  MultU64x32 (Timeout, TICKS_PER_MS)

+                  );

   if (EFI_ERROR (Status)) {

     return Status;

   }