backport: v3.7: dts: arm: st: stm32h5: fix spi 1-3 clocks

[erwango]

Backport issue to get #77923 backported on V3.7

Describe the bug

The STM32 SPI driver, spi_ll_stm32.c, reads the clock frequency via clock_control_get_rate(). The first clocks index is used as subsystem argument if there is no second index, but this is not the source clock for SPI 1, 2, and 3.
This causes the prescaler value calculation to be incorrect, resulting in a frequency potentially above the spi-max-frequency value.

Required fix

Add clock source for SPI instances 1, 2 and 3, that matches the default clock configuration register reset value, which resolves the issue.

[dkalowsk]

Closing as PR is merged.