sh: Get rid of nmi_count()

nmi_count() is a historical leftover and SH is the only user. Replace it
with regular per cpu accessors.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20201113141732.844232404@linutronix.de

arch/sh/kernel/irq.c

@@ -44,7 +44,7 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 
 	seq_printf(p, "%*s: ", prec, "NMI");
 	for_each_online_cpu(j)
-		seq_printf(p, "%10u ", nmi_count(j));
+		seq_printf(p, "%10u ", per_cpu(irq_stat.__nmi_count, j);
 	seq_printf(p, "  Non-maskable interrupts\n");
 
 	seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));

arch/sh/kernel/traps.c

@@ -186,7 +186,7 @@ BUILD_TRAP_HANDLER(nmi)
 	arch_ftrace_nmi_enter();
 
 	nmi_enter();
-	nmi_count(cpu)++;
+	this_cpu_inc(irq_stat.__nmi_count);
 
 	switch (notify_die(DIE_NMI, "NMI", regs, 0, vec & 0xff, SIGINT)) {
 	case NOTIFY_OK: