x86, efi: Convert printk to pr_*()

Alright, I guess I'll go through and convert them, even though
there's no net gain to speak of.

v4:
* Switched to pr_fmt and removed some redundant use of "EFI" in
  messages.

Signed-off-by: Olof Johansson <olof@lixom.net>
Link: http://lkml.kernel.org/r/1329081869-20779-3-git-send-email-olof@lixom.net


Cc: Joe Perches <joe@perches.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>