avr32: move NODES_SHIFT into Kconfig and delete numnodes.h

This patch moves the NODES_SHIFT symbol into Kconfig to synchronize AVR32
architecture with the current kernel. The global header files do longer use the
value from numnodes.h.

See commit c80d79d7 for details.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>