[X86]Enable the use of 'mov' with a 64bit GPR and a large immediate

Enable the next form (intel style):
"mov <reg64>, <largeImm>"
which is should be available,
where <largeImm> stands for immediates which exceed the range of a singed 32bit integer

Differential Revision: https://reviews.llvm.org/D28988

llvm-svn: 293030