drivers/base: use tabs where possible in code indentation

Linux kernel coding style require that tabs should be used instead of
spaces for code indentation.
Problem found using checkpatch.pl script.
Signed-off-by: NLavinia Tache <lavinia.tachee@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>