[HatoholArmPluginBase] Fix a compile time warning on 32bit environment

HatoholArmPluginBase.cc: In member function 'virtual void HatoholArmPluginBase::getTimeOfLastEvent(const TriggerIdType&)::Callback::onGotReply(mlpl::SmartBuffer&, const HapiCommandHeader&)':
HatoholArmPluginBase.cc:263:4: warning: narrowing conversion of 'time->HapiResTimeOfLastEvent::nsec' from 'const uint32_t {aka const unsigned int}' to '__syscall_slong_t {aka long int}' inside { } is ill-formed in C++11 [-Wnarrowing]
    };
    ^