Clear interrupt flags selectively
Clear interrupt flags selectively

As discussed in #1294, every time a CC13xx/CC26xx RF interrupt fires, we clear all interrupt flags unconditionally. This may result in missed events. This patch fixes this bug by clearing only the flag that triggered the interrupt in the first place.

Fixes #1294

MohamedSeliem/contiki,arurke/contiki,arurke/contiki,arurke/contiki,arurke/contiki,arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,arurke/contiki,arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki