PNP: Set up pnp_debug via module and not via boot param.

Cleanup only, no functional change (pnp.debug can be enabled
and disabled at runtime, but that's not a real enhancement).

This one depends on another PNP cleanup patch:
PNP: Compile all pnp built-in stuff in one module namespace
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/pnp/core.c

@@ -218,10 +218,5 @@ subsys_initcall(pnp_init);
 int pnp_debug;
 
 #if defined(CONFIG_PNP_DEBUG_MESSAGES)
-static int __init pnp_debug_setup(char *__unused)
-{
-	pnp_debug = 1;
-	return 1;
-}
-__setup("pnp.debug", pnp_debug_setup);
+module_param_named(debug, pnp_debug, int, 0644);
 #endif