ARM: at91: at91sam9g45: update defconfig

Update defconfig, adding:
 - PWM support using the generic framework
 - generic PWM leds
 - Power/reset
 - Watchdog

and removing deprecated config options.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>