dt-bindings: arm: stm32: Add compatible strings for ART-PI board

Art-pi based on stm32h750xbh6, with following resources:

-8MiB QSPI flash
-16MiB SPI flash
-32MiB SDRAM
-AP6212 wifi, bt, fm

detail information can be found at:
https://art-pi.gitee.io/website/



Signed-off-by: dillon min <dillon.minfei@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>