x86: make early_ioremap_debug early_param

This patch makes "early_ioremap_debug" a early parameter, because
"early_ioreamp/early_iounmap" is only used during early boot stage.

Signed-off-by: Huang Ying <ying.huang@intel.com>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>