[MIPS] DEC: Initialise ioasic_ssr_lock

Fix the definition of the ioasic_ssr_lock spinlock to include a proper 
initialisation.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/dec/setup.c b/arch/mips/dec/setup.c
index b8a5e75..3e634f2f 100644
--- a/arch/mips/dec/setup.c
+++ b/arch/mips/dec/setup.c
@@ -55,7 +55,7 @@
 
 int dec_tc_bus;
 
-spinlock_t ioasic_ssr_lock;
+DEFINE_SPINLOCK(ioasic_ssr_lock);
 
 volatile u32 *ioasic_base;