In the ARM Cortex-M architecture implementation, the concepts of
"exceptions" and "interrupts" are interchangeable; whereas, in the
Cortex-A/-R architecture implementation, they are considered separate
and therefore handled differently (i.e. `z_arm_exc_exit` cannot be used
to exit an "interrupt").
This commit fixes all `z_arm_exc_exit` usages in the interrupt handlers
to use `z_arm_int_exit`.
NOTE: In terms of the ARM AArch32 Cortex-A and Cortex-R architecture
implementations, the "exceptions" refer to the "Undefined
Instruction (UNDEF)" and "Prefetch/Data Abort (PABT/DABT)"
exceptions, while "interrupts" refer to the "Interrupt (IRQ)",
"Fast Interrupt (FIQ)" and "Software Interrupt/Supervisor Call
(SWI/SVC)".
Signed-off-by: Stephanos Ioannidis <root@stephanos.io>