ASoC: dt-bindings: stm32: Fix incorrect compatible string in stm32h7-sai match

The conditional block that defines clock constraints for the stm32h7-sai
variant references "st,stm32mph7-sai", which does not match any compatible
string in the enum. As a result, clock validation for the h7 variant is
silently skipped. Correct the compatible string to "st,stm32h7-sai".

Fixes: 8509bb1f11a1f ("ASoC: dt-bindings: add stm32mp25 support for sai")
Signed-off-by: Jihed Chaibi <jihed.chaibi.dev@gmail.com>
Reviewed-by: Olivier Moysan <olivier.moysan@foss.st.com>
Link: https://patch.msgid.link/20260321012011.125791-1-jihed.chaibi.dev@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>