sh: hw-breakpoint support requires perf events.

This follows the x86 change to select perf events when hw_breakpoint
support is enabled. This fixes up build issues where perf events can
otherwise be disabled on their own.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -43,6 +43,7 @@ config SUPERH32
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_ARCH_KGDB
 	select HAVE_HW_BREAKPOINT if CPU_SH4A
+	select PERF_EVENTS if HAVE_HW_BREAKPOINT
 	select ARCH_HIBERNATION_POSSIBLE if MMU
 
 config SUPERH64