xen/arm: irq: drop unreachable pirq callbacks

Since commit 341f271cf8 ("xen/evtchn: fully restrict concept of pIRQ for
arches with pIRQ support only"), the corresponding Arm arch pIRQ callbacks
become unreachable, so drop them.

Signed-off-by: Grygorii Strashko <grygorii_strashko@epam.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Denis Mukhin <dmukhin@ford.com>
Acked-by: Julien Grall <jgrall@amazon.com>

xen/arch/arm/irq.c

@@ -595,35 +595,6 @@ unlock:
     return ret;
 }
 
-/*
- * pirq event channels. We don't use these on ARM, instead we use the
- * features of the GIC to inject virtualised normal interrupts.
- */
-struct pirq *alloc_pirq_struct(struct domain *d)
-{
-    return NULL;
-}
-
-/*
- * These are all unreachable given an alloc_pirq_struct
- * which returns NULL, all callers try to lookup struct pirq first
- * which will fail.
- */
-int pirq_guest_bind(struct vcpu *v, struct pirq *pirq, int will_share)
-{
-    BUG();
-}
-
-void pirq_guest_unbind(struct domain *d, struct pirq *pirq)
-{
-    BUG();
-}
-
-void pirq_set_affinity(struct domain *d, int pirq, const cpumask_t *mask)
-{
-    BUG();
-}
-
 static bool irq_validate_new_type(unsigned int curr, unsigned int new)
 {
     return (curr == IRQ_TYPE_INVALID || curr == new );