treewide: correct the typo 'retun'

There are some spelling mistakes of 'retun' in comments which
should be instead of 'return'.

Link: https://lkml.kernel.org/r/63D0F870EE8E87A0+20240906054008.390188-1-wangyuli@uniontech.com


Signed-off-by: WangYuli <wangyuli@uniontech.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>