[X86] Properly account for the immediate being multiplied by 8 in the...

[X86] Properly account for the immediate being multiplied by 8 in the immediate range checking for BI__builtin_ia32_psrldqi128 and friends.

The limit was set to 1023 which only up to 127*8. It needs to be 2047 to allow 255*8.

llvm-svn: 334416