x86: Combine printk()s in show_regs_common()

Printing a single character alone when there's an immediately
following printk() is pretty pointless (and wasteful).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <4D5D535A0200007800032730@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>