IA64: Use early_parm to handle mvec_name and nomca

I'm not sure of the worthiness of this idea, so please consider it an RFC.
Its key merits are:

* Reuse existing infrastructure
* Greatly tightens up the parsing of nomca
* Greatly simplifies the parsing of machvec

Addition cleanup (moving setup_mvec() to machvec.c) by Ken Chen.

Signed-Off-By: Horms <horms@verge.net.au>
Signed-Off-By: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/machvec.c b/arch/ia64/kernel/machvec.c
index c3a04ee..4b0b71d 100644
--- a/arch/ia64/kernel/machvec.c
+++ b/arch/ia64/kernel/machvec.c
@@ -14,7 +14,15 @@
 struct ia64_machine_vector ia64_mv;
 EXPORT_SYMBOL(ia64_mv);
 
-static struct ia64_machine_vector *
+static __initdata const char *mvec_name;
+static __init int setup_mvec(char *s)
+{
+	mvec_name = s;
+	return 0;
+}
+early_param("machvec", setup_mvec);
+
+static struct ia64_machine_vector * __init
 lookup_machvec (const char *name)
 {
 	extern struct ia64_machine_vector machvec_start[];
@@ -33,10 +41,13 @@
 {
 	struct ia64_machine_vector *mv;
 
+	if (!name)
+		name = mvec_name ? mvec_name : acpi_get_sysname();
 	mv = lookup_machvec(name);
-	if (!mv) {
-		panic("generic kernel failed to find machine vector for platform %s!", name);
-	}
+	if (!mv)
+		panic("generic kernel failed to find machine vector for"
+		      " platform %s!", name);
+
 	ia64_mv = *mv;
 	printk(KERN_INFO "booting generic kernel on platform %s\n", name);
 }