x86: introduce show_fault_oops helper to fault_32|64.c

This will help when unifying the oops dumping code on 32/64
bit.  No functional changes.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>