IRQ related fixes (removed NMI, removed MTVECX, unified fast/fastx interrupts)
Created by: Silabs-ArjanB
IRQ related fixes as documented in https://github.com/openhwgroup/core-v-docs/issues/50.
- Removed NMI
- Unified fastx and fast interrupts
- Removed MTVECX
- Made irq_ack_o and irq_id_o apply to all interrupts
Fixes #243 (closed) #323 (closed) #336 (closed)
Signed-off-by: Arjan Bink Arjan.Bink@silabs.com