Remove assertion that's not true for !EARLY_AP_STARTUP

gtask->gt_taskqueue is NULL when EARLY_AP_STARTUP is not enabled.
Remove assertion to allow this config to work.

Reported by:	oleg
Sponsored by:	Limelight Networks

sys/net/iflib.c

@@ -5174,7 +5174,6 @@ iflib_irq_set_affinity(if_ctx_t ctx, int irq, iflib_intr_type_t type, int qid,
 	if (cpuid > ctx->ifc_cpuid_highest)
 		ctx->ifc_cpuid_highest = cpuid;
 #endif
-	MPASS(gtask->gt_taskqueue != NULL);
 	return 0;
 }