tests: mgmt: mcumgr: fs_mgmt_hash_supported: add unsupported platforms

- `stm32h745i_disco/stm32h745xx/m4` says "#error Flash driver on M4 core
  is not supported yet".
- `mpfs_icicle/polarfire/smp` fails in the compilation of the `spi_nor`
  flash driver.
- `cyw920829m2evk_02` fails to build because of undeclared
  `cyhal_nvm_*()` functions.

As a bonus, group the excluded platforms under the common part to
avoid repeating them.

Signed-off-by: Tomi Fontanilles <tomi.fontanilles@nordicsemi.no>