arch: Fix assert logic for installing shared interrupt

With this commit, it is now allowed to register any ISR and arg
combination for the same IRQ, except the case when the exact same
ISR-arg combination is already registered.

The previous assert logic had a restriction where the same ISR could not
be registered multiple times with different arguments.

Signed-off-by: Martin Åberg <martin.aberg@gaisler.com>

arch/common/shared_irq.c

@@ -92,8 +92,8 @@ void z_isr_install(unsigned int irq, void (*routine)(const void *),
 	for (i = 0; i < shared_entry->client_num; i++) {
 		client = &shared_entry->clients[i];
 
-		__ASSERT(client->isr != routine && client->arg != param,
-			 "trying to register duplicate ISR/arg pair");
+		__ASSERT((client->isr == routine && client->arg == param) == false,
+			 "ISR/arg combination is already registered");
 	}
 
 	shared_entry->clients[shared_entry->client_num].isr = routine;