dt-bindings: clock: Drop st,stm32h7-rcc.txt

The binding is already covered by st,stm32-rcc.yaml.

Signed-off-by: Rob Herring (Arm) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Acked-by: Conor Dooley <[email protected]>
Signed-off-by: Stephen Boyd <[email protected]>

Author: robherring