classmate-laptop: little optimization for cmpc_rfkill_block

We don't need to call bios/acpi (cmpc_set_rfkill_wlan) if the blocked
state is already set to the same value (little optimization). This can
happen for example if we initialize the module with same initial
hardware state (rfkill core always call cmpc_rfkill_block on
initialization here).

Also GWRI method only accepts 0 or 1 for setting rfkill block, as can be
seen on AML code from acpidump->DSDT from a classmate sample I have, so
should be fine setting state only to 0 or 1 directly.

Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>