Check reserved USB pages

PR #1010 points out that the reserved area of IFRAM for USB is inconsistent in Dabao. This is a deeper inconsistency than just the initial page reservation - looks like a change was made in baosec to improve the USB stack but was never mirrored over into dabao's config.

This issue is a reminder to look into this. At the moment, the impact is an over-reservation of space, so it doesn't break anything from a correctness standpoint, it just means we're wasting some memory that could otherwise be used for something else.