mmu_notifier.h: fix comment spelling

Signed-off-by: Figo.zhang <figo1802@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 4e02ee2..43dcfbd 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -227,7 +227,7 @@
 
 /*
  * These two macros will sometime replace ptep_clear_flush.
- * ptep_clear_flush is impleemnted as macro itself, so this also is
+ * ptep_clear_flush is implemented as macro itself, so this also is
  * implemented as a macro until ptep_clear_flush will converted to an
  * inline function, to diminish the risk of compilation failure. The
  * invalidate_page method over time can be moved outside the PT lock