MIPS: Remove incorrect NULL check in local_flush_tlb_page()

We check that the struct vm_area_struct pointer vma is NULL and then
dereference it a few lines below. The intent was to make sure vma is
not NULL but this is not necessary since the bug pre-dates GIT history
and seem to never have caused a problem. The tlb-4k and tlb-8k versions
of local_flush_tlb_page() don't bother checking if vma is NULL, also
vma is dereferenced before being passed to local_flush_tlb_page(),
thus it is safe to remove this NULL check.

Signed-off-by: Emil Goode <emilgoode@gmail.com>
Reviewed-by: Jonas Gorski <jogo@openwrt.org>
Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7264/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mm/tlb-r3k.c

@@ -158,7 +158,7 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 {
 	int cpu = smp_processor_id();
 
-	if (!vma || cpu_context(cpu, vma->vm_mm) != 0) {
+	if (cpu_context(cpu, vma->vm_mm) != 0) {
 		unsigned long flags;
 		int oldpid, newpid, idx;