stm32/rfcore: Enable RX IRQ on BLE IPCC channel for better performance.
stm32/rfcore: Enable RX IRQ on BLE IPCC channel for better performance.

Before this change there was up to a 128ms delay on incoming payloads from
CPU2 as it was polled by SysTick.  Now the RX IRQ immediately schedules the
PendSV.

pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython