mm: memcontrol: fix a typo in comment

Fix a spelling mistake in comment.

Link: https://lkml.kernel.org/r/20220815065102.74347-1-xu.panda@zte.com.cn


Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: xupanda <xu.panda@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>