Introduce BUS_PASS_SUPPORTDEV

The reason for this new pass is :

The earlier pass names are really specific (interrupt, timer, scheduler etc ..)
and making a driver that other device driver (that attach at DEFAULT pass)
needs probe at earlier pass can be confiusing. We can live with GPIO driver
at INTERRUPT pass because they are often an interrupt controller too but having
a usb phy driver probed at RESOURCES (or SCHEDULER for example) is silly.
The number was choosen to have a lot of margin if we want to introduce other
pass in the futur.

Reviewed by:	ian, imp, kevans
Differential Revision:	https://reviews.freebsd.org/D14568

sys/sys/bus.h

@@ -702,6 +702,7 @@ void	bus_data_generation_update(void);
 #define	BUS_PASS_INTERRUPT	40	/* Interrupt controllers. */
 #define	BUS_PASS_TIMER		50	/* Timers and clocks. */
 #define	BUS_PASS_SCHEDULER	60	/* Start scheduler. */
+#define	BUS_PASS_SUPPORTDEV	100000	/* Drivers which support DEFAULT drivers. */
 #define	BUS_PASS_DEFAULT	__INT_MAX /* Everything else. */
 
 #define	BUS_PASS_ORDER_FIRST	0