module: add more 'kernel-doc' comments

Some functions have the proper 'kernel-doc' comments but these don't start
with proper /** -- fix that, along with adding () to the function name on
the following lines to fully comply with the 'kernel-doc' format.

Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: Jessica Yu <jeyu@kernel.org>