sh64: provide a stub per_cpu_trap_init() definition.

This is needed to fix up the build at the moment. Gradually this will be
reworked to follow the 32-bit initialization path and deal with delayed
VBR initialization.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

arch/sh/kernel/traps_64.c

@@ -944,3 +944,8 @@ asmlinkage void do_debug_interrupt(unsigned long code, struct pt_regs *regs)
 	/* Clear all DEBUGINT causes */
 	poke_real_address_q(DM_EXP_CAUSE_PHY, 0x0);
 }
+
+void __cpuinit per_cpu_trap_init(void)
+{
+	/* Nothing to do for now, VBR initialization later. */
+}