Added LoadFirmware() API
Added LoadFirmware() API

Supports passing back the kernel sign key blob, and updating the
firmware data hash during decompression.  Doesn't require data for
both firmware volumes before deciding which one to boot.

Intended to replace VerifyFirmwareDriver_f().

Review URL: http://codereview.chromium.org/2691006

geekboxzone/mmallow_external_vboot_reference,coreboot/vboot,marineam/seismograph,geekboxzone/mmallow_external_vboot_reference,coreboot/vboot,acorn-marvell/vboot_reference,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,marineam/seismograph,ccaapton/vboot_reference,coreboot/vboot,acorn-marvell/vboot_reference,ionave/seismograph,acorn-marvell/vboot_reference,ccaapton/vboot_reference,ccaapton/vboot_reference,ionave/seismograph,ccaapton/vboot_reference,geekboxzone/mmallow_external_vboot_reference,coreboot/vboot,geekboxzone/mmallow_external_vboot_reference,marineam/seismograph,marineam/seismograph,acorn-marvell/vboot_reference,ionave/seismograph