vboot: rename USB to more accurate EXTERNAL

Rename enumerators of the vb2_dev_default_boot_target enum as follows,
because the term USB is not quite accurate (we can also boot from an SD
card).

 VB2_DEV_DEFAULT_BOOT_TARGET_DISK
 --> VB2_DEV_DEFAULT_BOOT_TARGET_INTERNAL

 VB2_DEV_DEFAULT_BOOT_TARGET_USB
 --> VB2_DEV_DEFAULT_BOOT_TARGET_EXTERNAL

Also perform similar renaming for the following.

enum vb2_nv_param:
 VB2_NV_DEV_BOOT_USB
 --> VB2_NV_DEV_BOOT_EXTERNAL

enum vb2_secdata_fwmp_flags:
 VB2_SECDATA_FWMP_DEV_ENABLE_USB
 --> VB2_SECDATA_FWMP_DEV_ENABLE_EXTERNAL

constants:
 VB2_NV_DEV_FLAG_USB
 --> VB2_NV_DEV_FLAG_EXTERNAL

functions:
 vb2_dev_boot_usb_allowed
 --> vb2_dev_boot_external_allowed

BRANCH=none
BUG=none
TEST=make runtests

Change-Id: Iad16fcf34d76da08c6d8a81e150c7fde927c743b
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2237622
Reviewed-by: Joel Kitching <kitching@chromium.org>
19 files changed