boards: nucleo_wb55rg: Give more flash space to M0 binary

Since version 1.11.0, Full stack M0 binary requires 216K of flash
being available, while previously 212K were required.

Review flash partitioning to take it into account.
Additionally:
- update value in board yaml file.
- align value in package .dtsi file

Fixes #38735

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>