firmware: use () to terminate kernel-doc function names

The kernel-doc spec dictates a function name ends in ().

Signed-off-by: Andres Rodriguez <andresx7@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
[mcgrof: adjust since the wide API rename is not yet merged]
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>