ixv(4): Stop setting editing ifnet flags in ixv_if_init()

In iflib, the device-specific init() function isn't supposed to edit
the struct ifnet driver flags. If it does, it'll cause an MPASS() assert
in iflib to fail.

PR:		225312
Reported by:	bhughes@

sys/dev/ixgbe/if_ixv.c

@@ -662,10 +662,6 @@ ixv_if_init(if_ctx_t ctx)
 	/* And now turn on interrupts */
 	ixv_if_enable_intr(ctx);
 
-	/* Now inform the stack we're ready */
-	ifp->if_drv_flags |= IFF_DRV_RUNNING;
-	ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
-
 	return;
 } /* ixv_if_init */