Add module version to iwi/ipw/wpi and iwn.

The version is used to check if a module is already preset, not setting
it results in:

can't re-use a leaf (ipw)!
module_register: module pci/ipw already exists!
Module pci/ipw failed to register: 17

while trying to load the module due to an entry in loader.conf. With this
commit we get the expected:

module ipw already present!

Reported by:	Dru Lavigne, bz
Tested by:	bz
MFC after:	1 week

sys/dev/ipw/if_ipw.c

@@ -199,6 +199,8 @@ static devclass_t ipw_devclass;
 
 DRIVER_MODULE(ipw, pci, ipw_driver, ipw_devclass, 0, 0);
 
+MODULE_VERSION(ipw, 1);
+
 static int
 ipw_probe(device_t dev)
 {

sys/dev/iwi/if_iwi.c

@@ -232,6 +232,8 @@ static devclass_t iwi_devclass;
 
 DRIVER_MODULE(iwi, pci, iwi_driver, iwi_devclass, 0, 0);
 
+MODULE_VERSION(iwi, 1);
+
 static __inline uint8_t
 MEM_READ_1(struct iwi_softc *sc, uint32_t addr)
 {

sys/dev/iwn/if_iwn.c

@@ -401,6 +401,8 @@ static devclass_t iwn_devclass;
 
 DRIVER_MODULE(iwn, pci, iwn_driver, iwn_devclass, 0, 0);
 
+MODULE_VERSION(iwn, 1);
+
 MODULE_DEPEND(iwn, firmware, 1, 1, 1);
 MODULE_DEPEND(iwn, pci, 1, 1, 1);
 MODULE_DEPEND(iwn, wlan, 1, 1, 1);

sys/dev/wpi/if_wpi.c

@@ -273,6 +273,8 @@ static devclass_t wpi_devclass;
 
 DRIVER_MODULE(wpi, pci, wpi_driver, wpi_devclass, 0, 0);
 
+MODULE_VERSION(wpi, 1);
+
 static const uint8_t wpi_ridx_to_plcp[] = {
 	/* OFDM: IEEE Std 802.11a-1999, pp. 14 Table 80 */
 	/* R1-R4 (ral/ural is R4-R1) */