powerpc: Add HAVE_IRQ_TIME_ACCOUNTING

Allow us to enable IRQ_TIME_ACCOUNTING. Even though we currently
use VIRT_CPU_ACCOUNTING_NATIVE, that option is quite heavy
weight and IRQ_TIME_ACCOUNTING might be better in some cases.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/Kconfig

@@ -208,6 +208,7 @@ config PPC
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_VIRT_CPU_ACCOUNTING
+	select HAVE_IRQ_TIME_ACCOUNTING
 	select IRQ_DOMAIN
 	select IRQ_FORCED_THREADING
 	select MODULES_USE_ELF_RELA