cputime: Generalize CONFIG_VIRT_CPU_ACCOUNTING

S390, ia64 and powerpc all define their own version
of CONFIG_VIRT_CPU_ACCOUNTING. Generalize the config
and its description to a single place to avoid
duplication.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 30fd01d..72afd28 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -1,6 +1,7 @@
 config PPC64
 	bool "64-bit kernel"
 	default n
+	select HAVE_VIRT_CPU_ACCOUNTING
 	help
 	  This option selects whether a 32-bit or a 64-bit kernel
 	  will be built.
@@ -337,21 +338,6 @@
 	default y if (!PPC_FSL_BOOK3E && PPC64 && HUGETLB_PAGE) || (PPC_STD_MMU_64 && PPC_64K_PAGES)
 	default n
 
-config VIRT_CPU_ACCOUNTING
-	bool "Deterministic task and CPU time accounting"
-	depends on PPC64
-	default y
-	help
-	  Select this option to enable more accurate task and CPU time
-	  accounting.  This is done by reading a CPU counter on each
-	  kernel entry and exit and on transitions within the kernel
-	  between system, softirq and hardirq state, so there is a
-	  small performance impact.  This also enables accounting of
-	  stolen time on logically-partitioned systems running on
-	  IBM POWER5-based machines.
-
-	  If in doubt, say Y here.
-
 config PPC_HAVE_PMU_SUPPORT
        bool