[POWERPC] pseries: phyp dump: Disable phyp-dump through boot-var

This adds a kernel command line option "phyp_dump", which takes a 0/1
value for disabling/ enabling phyp_dump at boot time.  Kdump can use
this on cmdline (phyp_dump=0) to disable phyp-dump during boot when
enabling itself.  This will ensure only one dumping mechanism is active
at any given time.

Signed-off-by: Manish Ahuja <mahuja@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/prom.c

@@ -1060,6 +1060,11 @@ static void __init phyp_dump_reserve_mem(void)
 		return;
 	}
 
+	if (!phyp_dump_info->phyp_dump_at_boot) {
+		printk(KERN_INFO "Phyp-dump disabled at boot time\n");
+		return;
+	}
+
 	if (phyp_dump_info->phyp_dump_is_active) {
 		/* Reserve *everything* above RMR.Area freed by userland tools*/
 		base = PHYP_DUMP_RMR_END;