sparc64: Implement perf_arch_fetch_caller_regs

We provide regs->tstate, regs->tpc, regs->tnpc and
regs->u_regs[UREG_FP].

regs->tstate is necessary for:

	user_mode()		(via perf_exclude_event())

	perf_misc_flags()	(via perf_prepare_sample())

regs->tpc is necessary for:

	perf_instruction_pointer() (via perf_prepare_sample())

and regs->u_regs[UREG_FP] is necessary for:

	perf_callchain()	(via perf_prepare_sample())

The regs->tnpc value is provided just to be tidy.

Signed-off-by: David S. Miller <davem@davemloft.net>