clk_fixed: call clkdom_dump() for verbose boot

This is standard practice for clock drivers that register clocks
dynamically. Nothing else uses the CLK_DEBUG macro.

The result is that the name and frequency of the fixed clock is printed
for a verbose boot, which may aid in debugging.

Reviewed by:	manu
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D44265

sys/dev/clk/clk_fixed.c

@@ -258,9 +258,10 @@ clk_fixed_attach(device_t dev)
 		rv = ENXIO;
 		goto fail;
 	}
-#ifdef CLK_DEBUG
-	clkdom_dump(sc->clkdom);
-#endif
+
+	if (bootverbose)
+		clkdom_dump(sc->clkdom);
+
 	OF_prop_free(__DECONST(char *, def.clkdef.name));
 	OF_prop_free(def.clkdef.parent_names);
 	return (bus_generic_attach(dev));