device ram size is 40 kb, not 48 kB

[JojoS62]

Summary of changes

This fix is for correcting the ram size of F303CC device.
In total RAM+RAM1 it has 48 kB, but the regions are not continuous. SRAM has 40 kB, when 48 kB is set in the linker script, then the device fails to start because the stack pointer is in the Nirvana.

This error is also in arm-pack index.json in Mbed-OS.

Impact of changes

Important fix for this device. Currently, no boards are using this. It is a basically needed for new target ROBOTDYN_F303CC
(also called Blackpill F303, small Chinese breakout board).

Migration actions required

Documentation

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Pull request type

[X] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

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Test results

[] No Tests required for this change (E.g docs only update)
[] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

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Reviewers

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[JojoS62]

thanks for reviewing,
I have changed the PR status to draft, because I want to add the remaning 8 kB of RAM in another section, so that it can be used also.

[JojoS62]

I have send this PR to mbed-os and it is already merged. Can it be merged from there also to mbed-ce?
ARMmbed#15378