[spibus] small code refactoring

Merge 3 sequential printf calls into one.

Reported by:	rpokala
Reviewed by:	rpokala, adrian
Approved by:	adrian (mentor)
Differential Revision:	https://reviews.freebsd.org/D8795

sys/dev/spibus/spibus.c

@@ -116,9 +116,8 @@ spibus_probe_nomatch(device_t bus, device_t child)
 {
 	struct spibus_ivar *devi = SPIBUS_IVAR(child);
 
-	device_printf(bus, "<unknown card>");
-	printf(" at cs %d", devi->cs);
-	printf(" mode %d\n", devi->mode);
+	device_printf(bus, "<unknown card> at cs %d mode %d\n", devi->cs,
+	    devi->mode);
 	return;
 }