move RXLEN definition into the C file which solely needs it

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
move state_[bcm|raw|control] definitions

Having separate include files containing exactly one function is pointless
and only pollutes the file list. Move the definitions to the already
existing socketcand.h which is included by all C files anyway.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Add generated debian_pack to distclean for removal

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>