sh: Provide cpu_idle_wait() to fix up cpuidle/SMP build.

Crib the x86 cpu_idle_wait() implementation and shove it in with the
idle code, subsequently enabling ARCH_HAS_CPU_IDLE_WAIT.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index ac1c620..09c0aef 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -151,6 +151,9 @@
 config ARCH_HAS_DEFAULT_IDLE
 	def_bool y
 
+config ARCH_HAS_CPU_IDLE_WAIT
+	def_bool y
+
 config IO_TRAPPED
 	bool