i386: consolidate show_regs and show_registers for i386

Both functions printk the same information, except for CRx and
debug registers in the show_registers() one and a bit different
manner. So move the common code into one place. This is already
done for x86_64, so I think it's worth having the same on i386.

This saves 100 bytes of .rodata section :) ...
   but only 8 from .text :(

[ tglx: arch/x86 adaptation ]

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>