Fix mpr(4) panic during a firmware update.

Issue Description:
The RequestCredits field of IOCFacts got changed between the Phase23
firmware to Phase24 firmware. So as part of firmware update operation,
driver has to free the resources & pools which are created with the Phase23
Firmware's IOCFacts data (i.e. during driver load time) and has to
reallocate the resources and pools using Phase24's IOCFacts data. Here
driver has freed the interrupts but missed to reallocate the interrupts and
hence config page read operation is getting timed out and controller is
going for recursive reinit (controller reset) operations and leading to
kernel panic.

Fix:
Reallocate the interrupts if the interrupts are disabled as part of
firmware update/downgrade operation.

Submitted by:	Sreekanth Ready <sreekanth.reddy@broadcom.com>
Tested by:	ken
MFC after:	3 days

sys/dev/mpr/mpr.c

@@ -740,7 +740,7 @@ mpr_iocfacts_allocate(struct mpr_softc *sc, uint8_t attaching)
 	 * XXX If the number of MSI-X vectors changes during re-init, this
 	 * won't see it and adjust.
 	 */
-	if (attaching && (error = mpr_pci_setup_interrupts(sc)) != 0) {
+	if ((attaching || reallocating) && (error = mpr_pci_setup_interrupts(sc)) != 0) {
 		mpr_dprint(sc, MPR_INIT|MPR_ERROR,
 		    "Failed to setup interrupts\n");
 		mpr_free(sc);