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.