avr32: allow system timer to share interrupt to make OProfile work

The following patch allows the avr32_comparator interrupt to be shared.
This is necessary as the avr32 oprofile driver shares the irq group 0
with the timer.

To make OProfile actually work on AVR32, a small patch for oprofiled is
also needed (posted to the oprofile mailing list).

Signed-off-by: Nikolaus Voss <n.voss@weinmann.de>
[haavard.skinnemoen@atmel.com: set IRQF_SHARED unconditionally]
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>