Driver core: rename ktype_edd and ktype_efivar

This makes it a bit more sane when trying to figure out how to clean up
the ktype mess.

Based on a larger patch from Kay Sievers

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>