[MIPS] DEC: Initialise ioasic_ssr_lock

Fix the definition of the ioasic_ssr_lock spinlock to include a proper 
initialisation.
Signed-off-by: NMaciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/dec/setup.c

@@ -55,7 +55,7 @@ EXPORT_SYMBOL(dec_kn_slot_size);
 
 int dec_tc_bus;
 
-spinlock_t ioasic_ssr_lock;
+DEFINE_SPINLOCK(ioasic_ssr_lock);
 
 volatile u32 *ioasic_base;