x86: Resume trampoline must be executable

commit 5bd5a452

(x86: Add NX protection for kernel data) marked the
trampoline area NX - which unsurprisingly breaks resume and cpu
hotplug.

Revert the portion of that commit, which touches the trampoline.

Originally-from: Lin Ming <ming.m.lin@intel.com>
LKML-Reference: <1290410581.2405.24.camel@minggr.sh.intel.com>
Cc: Matthieu Castet <castet.matthieu@free.fr>
Cc: Siarhei Liakh <sliakh.lkml@gmail.com>
Cc: Xuxian Jiang <jiang@cs.ncsu.edu>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>
Tested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>