cros_bundle_firmware: Select u-boot or u-boot.elf for x86

When using coreboot we need the elf file, not the binary. Select this
automatically for now.

Another solution might be to add a separate parameter for specifying a
U-Boot elf file, or perhaps explicitly requiring that the correct one
should be given. In the transition this method is convenient, though,
since we don't break any ebuilds.

BUG=chrome-os-partner:7969
TEST=manual
Use 'cros_bundle_firmware -u' with a u-boot.bin and see that it correctly
picks up the u-boot elf file instead.

Change-Id: I07ec26f30b121a8d3d7c251918080b59c2e196b2
Reviewed-on: https://gerrit.chromium.org/gerrit/24769
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Commit-Ready: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
1 file changed