parisc: Optimize switch_mm

We only need to switch contexts when prev != next, and we don't need to
disable interrupts to do the check.

Signed-off-by: John David Anglin <[e-mail]>
Signed-off-by: Helge Deller <[e-mail]>

arch/parisc/include/asm/mmu_context.h

···
 {
 	unsigned long flags;
 
+	if (prev == next)
+		return;
+
 	local_irq_save(flags);
 	switch_mm_irqs_off(prev, next, tsk);
 	local_irq_restore(flags);