parisc: implement atomic64_dec_if_positive()

Signed-off-by: Helge Deller <deller@gmx.de>
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 433e75a..fe4afb0 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -13,6 +13,7 @@
 	select BUG
 	select HAVE_PERF_EVENTS
 	select GENERIC_ATOMIC64 if !64BIT
+	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select HAVE_GENERIC_HARDIRQS
 	select BROKEN_RODATA
 	select GENERIC_IRQ_PROBE