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/s390/Kconfig b/arch/s390/Kconfig
index 76de6b6..49ebfb6 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -49,9 +49,6 @@
 config PGSTE
 	def_bool y if KVM
 
-config VIRT_CPU_ACCOUNTING
-	def_bool y
-
 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	def_bool y
 
@@ -89,6 +86,8 @@
 	select HAVE_MEMBLOCK
 	select HAVE_MEMBLOCK_NODE_MAP
 	select HAVE_CMPXCHG_LOCAL
+	select HAVE_VIRT_CPU_ACCOUNTING
+	select VIRT_CPU_ACCOUNTING
 	select ARCH_DISCARD_MEMBLOCK
 	select BUILDTIME_EXTABLE_SORT
 	select ARCH_INLINE_SPIN_TRYLOCK