Fix: Declare correct RAM sizes for STM32F7

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Detailed description

• No new features.
• The existing problem is RTT Auto Search triggering lots of SWD Fault past end of physical SRAM on STM32F722.
• This PR solves it by shrinking declared memory map and dispatching datasheet values per-family.

As I've tried to inspect/debug a project on a board involving STM32F722, the RTT Auto Search feature (which is supposed to be plug&play without configuration) started scrubbing available RAM but fell off the 192 KiB cliff trying to scan all 384 KiB of AHB SRAM which should be present on STM32F777. Confirmed with blackpill-f411ce and BMDA. I know about mon rtt mem ranges but this sounds more like a workaround rather than fix, BMD should provide knowledge of DUT flash and RAM maps and sizes.

Note this was not rigorously tested with a real project yet. I don't like the seven function calls, this can be further reduced to three via stack locals, should be cheaper than a full LUT. Update: reduced, was +80, now is +48 bytes size-diff.
Tested on STM32F722RE to no longer generate "SWD access resulted in fault" messages during reads outside RAM bounds, and to create a smaller correct RAM map.

Your checklist for this pull request

• I've read the Code of Conduct
• I've read the guidelines for contributing to this repository
• It builds for hardware native (see Building the firmware)
• It builds as BMDA (see Building the BMDA)
• I've tested it to the best of my ability
• My commit messages provide a useful short description of what the commits do

Closing issues

Fixes #2006.

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Seven function calls costed more flash than two calls, so the #1710 approach is not optimal either.
Clarify whether I should also add the 8 datasheets and 3 reference manuals (RM0385, RM0410, RM0431) for STM32F7 to top of file.
I also have a minor fix for ITCM inconsistency for a follow-up PR, but it worsens blank_check behaviour (will check twice). Finally, I also will have a medium fix for STM32F4 RAM being pinned to 320kiB which is too blanket, in another PR.