platform/chrome: cros_ec_debugfs: fix kernel-doc warning

Fix the following kernel-doc warning:

$ ./scripts/kernel-doc -none drivers/platform/chrome/*
[...]
warning: This comment starts with '/**', but isn't a kernel-doc comment.

Fixes: 14bb09b32f43 ("platform/chrome: cros_ec: Separate logic for getting panic info")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Benson Leung <bleung@chromium.org>
Link: https://lore.kernel.org/r/20230411053308.1572493-1-tzungbi@kernel.org