openrisc: enable LOCKDEP_SUPPORT and irqflags tracing

Lockdep is needed for proving the spinlocks and rwlocks work fine on our
platform.  It also requires calling the trace_hardirqs_off() and
trace_hardirqs_on() pair of routines when entering and exiting an
interrupt.

For OpenRISC the interrupt stack frame does not support frame pointers,
so to call trace_hardirqs_on() and trace_hardirqs_off() here the macro's
build up a stack frame each time.

There is one necessary small change in _sys_call_handler to move
interrupt enabling later so they can get re-enabled during syscall
restart. This was done to fix lockdep warnings that are now possible due
to this
patch.

Signed-off-by: Stafford Horne <shorne@gmail.com>
diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index 399f55e..f8cfb3b 100644
--- a/arch/openrisc/Kconfig
+++ b/arch/openrisc/Kconfig
@@ -64,6 +64,9 @@
 config STACKTRACE_SUPPORT
 	def_bool y
 
+config LOCKDEP_SUPPORT
+	def_bool  y
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"