atm: atmdev: add function parameter names and description

atm: atmdev: add function parameter names and description

kernel-doc reports function parameters not described for parameters
that are not named. Add parameter names for these functions and then
describe the function parameters in kernel-doc format.

Fixes these warnings:
Warning: include/linux/atmdev.h:316 function parameter '' not described
 in 'register_atm_ioctl'
Warning: include/linux/atmdev.h:321 function parameter '' not described
 in 'deregister_atm_ioctl'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://patch.msgid.link/20260228220845.2978547-1-rdunlap@infradead.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>