Radio pin interrupt sometime not registered

[RobTWTG]

When further investigating this old issue: #77
I observed that sometimes a RX_DONE task is not finished properly, and the lbm will still panic like this:

[ERR ][LHAL]: function: rp_callback, line: 443 [ERR ][LHAL]: RP_FAILSAFE - #2

I noticed that in the rp_callback function the 1st thing that gets done is smtc_modem_hal_disable_modem_irq( ); disabling the timer and pin interrupts.

With overlapping tasks (like managing ping slots for class B) It looks like there is a chance that radio pin interrupts can be missed. Because rp_callback is called periodically.

I ran a simple test removing all functionality from smtc_modem_hal_disable_modem_irq so not disabling the interrupts anymore, and the panics disappeared.

Hopefully this can get looked into.

Many thanks,
Best regards