soc: arm: Add support for STM32H730xxQ

The STM32H730 series has a variant built with SMPS. It uses
`stm32h730xxq.h` header file instead of `stm32h730xx.h`, which has the
SMPS macro defined.

This commit adds the `SOC_STM32H730XXQ` configuration option to allow
the build system include the proper header file. With this change,
boards can enable `CONFIG_POWER_SUPPLY_DIRECT_SMPS` to set up the power
supply for the CPU.

Signed-off-by: Chen Xingyu <hi@xingrz.me>