Fix Memory Size for STM32G4...6/8 and STM32G4[34]..B

[AdinAck]

The memory size for these chips was set to 20 KiB instead of 32. Perhaps a hex to dec conversion error.

Evidence that the correct size is 32 KiB:
STM32G4xxxx
STM32G441RB

Thanks!

[embassy-ci]

diff: https://ci.embassy.dev/jobs/acdf4e0dbafc/artifacts/diff.html

[AdinAck]

After looking closer at the datasheet I actually don't know how to modify the invocation of mem! to accurately represent the SRAM banks in these chips, but 20 KiB is still certainly wrong so I will change this to an issue.

[embassy-ci]

diff: https://ci.embassy.dev/jobs/073da65a88c9/artifacts/diff.html

[AdinAck]

woops: #301

[Dirbaio]

thanks!