avr32: update defconfig to use the generic PWM framework

Now that all boards have switched to the generic PWM framework, update the
defconfigs to use it.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>