[Sparc] allow tls_add/tls_call syntax in assembler parser

Summary: Removing unneeded isCodeGenOnly from tls-specific
instructions - TLS_ADD/TLS_LD/TLS_LDX/TLS_CALL.

Author: fedor.sergeev

Reviewers: jyknight, fedor.sergeev

Reviewed By: jyknight

Subscribers: dcederman, brad, llvm-commits

Differential Revision: https://reviews.llvm.org/D36463

llvm-svn: 341308