[NVPTX] shfl.sync is introduced in PTX 6.0

PTX ISA spec, s9.7.8.6. Data Movement and Conversion Instructions:
shfl.sync

PTX ISA Notes
Introduced in PTX ISA version 6.0.

Target ISA Notes
Requires sm_30 or higher.

Differential Revision: https://reviews.llvm.org/D123039