powerpc/kvm: Remove unused references for MMCR3/SIER2/SIER3 registers

Commit 57dc0eed ("KVM: PPC: Book3S HV P9: Implement PMU save/restore
in C") removed the PMU save/restore functions from assembly code and
implemented these functions in C, for power9 and later platforms.

After the code refactoring, Performance Monitoring Unit (PMU) registers
became part of "p9_host_os_sprs" structure and now this structure is
used to save/restore pmu host registers, for power9 and later platfroms.
But we still have old unused registers references. Patch removes unused
host_mmcr references for Monitor Mode Control Register 3 (MMCR3)/
Sampled Instruction Event Register 2 (SIER2)/ SIER3 registers from
"struct kvmppc_host_state".

Fixes: 57dc0eed ("KVM: PPC: Book3S HV P9: Implement PMU save/restore in C")
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220916105736.268153-3-disgoel@linux.vnet.ibm.com

arch/powerpc/include/asm/kvm_book3s_asm.h

@@ -105,7 +105,7 @@ struct kvmppc_host_state {
 	void __iomem *xive_tima_virt;
 	u32 saved_xirr;
 	u64 dabr;
-	u64 host_mmcr[10];	/* MMCR 0,1,A, SIAR, SDAR, MMCR2, SIER, MMCR3, SIER2/3 */
+	u64 host_mmcr[7];	/* MMCR 0,1,A, SIAR, SDAR, MMCR2, SIER */
 	u32 host_pmc[8];
 	u64 host_purr;
 	u64 host_spurr;