Merge branch 'add-support-cpu-v4-insns-for-rv64'

Merge branch 'add-support-cpu-v4-insns-for-rv64'

Pu Lehui says:

====================
Add support cpu v4 insns for RV64

Add support cpu v4 instructions for RV64. The relevant tests have passed as show bellow:

Summary: 6/166 PASSED, 0 SKIPPED, 0 FAILED

NOTE: ldsx_insn testcase uses fentry and needs to rely on ftrace direct call [0].
[0] https://lore.kernel.org/all/20230627111612.761164-1-suagrfillet@gmail.com/

v2:
- Use temporary reg to avoid clobbering the source reg in movs_8/16 insns. (Björn)
- Add Acked-by

v1:
https://lore.kernel.org/bpf/20230823231059.3363698-1-pulehui@huaweicloud.com
====================

Tested-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230824095001.3408573-1-pulehui@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>