feat(dt-bindings): add bindings for STM32MP13

Add dedicated clock and reset dt-bindings include files. The former
files are renamed with stm32mp15, and the stm32mp1 file just
determine through STM32MP13 or STM32MP15 flag which file to include.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I0db23996a3ba25f7c3ea920f16230b11cf051208