crosvm: arm64: Move image loading code in lib.rs
crosvm: arm64: Move image loading code in lib.rs

Move the block handling image loading above the code initializing vCPUs
to make an upcoming patch clearer: no functional change intended.

BUG=b:203505371
TEST=presubmit

Change-Id: Ie215a58de942dd5eceff5df46016bd17fafcf5ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3259936
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Pierre-Clément Tosi <2823ff726385ec3ac1cbf6edb75016ef1c0f9dc0@google.com>
Reviewed-by: Andrew Walbran <91a7c1b7f9f624e0ed1b099dc85ecb6025941ee9@google.com>
Reviewed-by: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm