Input: atkbd - allow setting force-release bitmap via sysfs

There are more and more laptop requiring use of force_release quirk
for their multimedia and other specialized keys. Adding their DMI data
to the kernel is not sustainable; instead we will rely on help from
userspace (HAL) to do that for us.

This patch creates a new 'force_release' sysfs attribute (that belongs
to serio device to which keyboard is attached) which can be used to set
up force_release keymap. For example, Dell laptop owners might do:

echo 133-139,143,147 > /sys/devices/platform/i8042/serio0/force_release

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>