Used partitions and configfile bootloader attributes instead of
using getters get_bootloader_file and get_partitions.
(From OE-Core rev: d34dd190e1da00ca8c9b2cb0adba15b9f0de2920)
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>