x86: setup_percpu.c: Use pr_<level> and add pr_fmt(fmt)

- Added #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 - Stripped PERCPU: from a pr_warning

Signed-off-by: Joe Perches <joe@perches.com>
LKML-Reference: <7ead24eccbea8f2b11795abad3e2893a98e1e111.1260383912.git.joe@perches.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>