Fix uVisor overlap detection

- uVisor only can detect overlaps on Freescale K64F peripherals (v7M)
- needs to detect overlaps on bitband-aliases of peripherals (won't detect overlap right now)
- needs to block SRAM sharing due future RPC/IPC RTOS support
- only matching overlap are allowed, no partial overlaps are be encouraged unless we find a good reason to allow partial overlaps.

To resolve the bug we might block sharing attempts on all unsupported platforms or bitband aliases and keep this issue open minus the bug-tag.

@AlessandroA

Begin by locating uVisor's overlap-detection entry point and the platform-specific handling for Freescale K64F peripherals. Check how bitband aliases, SRAM sharing, unsupported platforms, and partial overlaps are represented, then inspect any existing overlap tests. Done means the supported sharing rules are enforced consistently, with behavior for unsupported cases documented or covered by tests.

Written by the indexing model from the issue text.