Replace /* */ comment with //, fix SPDX comment style.

see: Documentation/process/license-rules.rst

Link: https://lkml.kernel.org/r/1614223348-15516-1-git-send-email-daizhiyuan@phytium.com.cnSigned-off-by: NZhiyuan Dai <daizhiyuan@phytium.com.cn>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>