Fix fwupx64.efi not actually staging capsules properly. (#80)

[superm1]

Bisecting master shows that the problem was introduced in 6f63cdd.

When the guid_cmp comparison was put in place it flipped the logic
of one of the checks.

git bisect start 'efi/'
bad: [5c2a8d0] efi: better debugging on our capsule tests.
git bisect bad 5c2a8d0
good: [04daa63] Make SUBDIRS overrideable
git bisect good 04daa63
good: [cd9ea4c] efi: delete the boot path from the BootOrder list
git bisect good cd9ea4c
good: [515b0c0] Fix capsule sizes for our ux image capsules
git bisect good 515b0c0
bad: [6f63cdd] efi: Add guid_cmp() and remove manual comparisons.
git bisect bad 6f63cdd
good: [55ed685] Reorganize Make.version a bit so "bumpver" works better.
git bisect good 55ed685
good: [75391bc] Adding capsule headers should add flags if it's /not/ a ux cap.
git bisect good 75391bc
first bad commit: [6f63cdd] efi: Add guid_cmp() and remove manual comparisons.

[vathpela]

Thanks, I've pushed this to master.