staging: vt6655: refactor camelcase byMaxPwrLevel to max_pwr_level

Replace hungarian notated variable "byMaxPwrLevel" with "max_pwr_level"
compliant with linux kernel coding style.

Signed-off-by: Alberto Merciai <alb3rt0.m3rciai@gmail.com>
Link: https://lore.kernel.org/r/20211119081656.GA12982@alb3rt0-VirtualBox


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>