include/dt-bindings: clocks: stm32h7: Use _C1_ registers offset

STM32H7 series offer alias addresses to access some registers that could
be accessed by the M4 core on dual core variants.
For instance RCC_AHB3ENR could be accessed at following offsets:
- 0x0D4: Accessible from both cores
- 0x134: Accessible from C1 (M7) core
- 0x194: Accessible from C2 (M4) core (if any)

For most single core H7 variants, the two first addresses were accessible,
but for some others (stm32h7ax/stm32h7bx), only the 'C1 accessible'
was available.

This fact used to be hidden by the use of LL API to access these registers,
providing the required abstraction (an mainly using the first alias
when possible to simplify implementation).

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>