drivers: base: Use __printf markup to silence compiler

Silence warnings (triggered at W=1) by adding relevant __printf
attributes.

  drivers/base/cpu.c:432:2: warning: function '__cpu_device_create' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]

Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>