powerpc/perf: Add support for ISA3.1 PMU SPRs

PowerISA v3.1 includes new performance monitoring unit(PMU)
special purpose registers (SPRs). They are

Monitor Mode Control Register 3 (MMCR3)
Sampled Instruction Event Register 2 (SIER2)
Sampled Instruction Event Register 3 (SIER3)

MMCR3 is added for further sampling related configuration
control. SIER2/SIER3 are added to provide additional
information about the sampled instruction.

Patch adds new PPMU flag called "PPMU_ARCH_31" to support handling of
these new SPRs, updates the struct thread_struct to include these new
SPRs, include MMCR3 in struct mmcr_regs. This is needed to support
programming of MMCR3 SPR during event_enable/disable. Patch also adds
the sysfs support for the MMCR3 SPR along with SPRN_ macros for these
new pmu SPRs.

Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
[mpe: Rename to PPMU_ARCH_31 as noted by jpn]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1594996707-3727-5-git-send-email-atrajeev@linux.vnet.ibm.com