MIPS: DEC: Export `ioasic_ssr_lock' to modules

Fix a modular `declance' regression caused by LMO commit bb46bf30d13f
("DECstation SCSI driver clean-ups.")
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13256/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/dec/setup.c

@@ -60,6 +60,7 @@ EXPORT_SYMBOL(dec_kn_slot_size);
 int dec_tc_bus;
 
 DEFINE_SPINLOCK(ioasic_ssr_lock);
+EXPORT_SYMBOL(ioasic_ssr_lock);
 
 volatile u32 *ioasic_base;