stm32mp157c evaluation board has TIM2_CH4, TIM8_CH4 and TIM12_CH1
available on GPIO expansion connector.
Add PWM and associated triggers (for ADC/DAC) on these timers.
Keep them disabled so these pins can be used as GPIOs by default.
Signed-off-by: NFabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: NAlexandre Torgue <alexandre.torgue@st.com>

Add support of stm32mp157c evaluation board (part number: STM32MP157C-EV1)
split in 2 elements:
-Daughter board (part number: STM32MP157C-ED1)
 which includes CPU, memory and power supply
-Mother board (part number: STM32MP157C-EM1)
 which includes external peripherals (like display, camera,...)
 and extension connectors.

The daughter board can run alone, this is why the device tree files
are split in two layers, for the complete evaluation board (ev1)
and for the daughter board alone (ed1).
Signed-off-by: NLudovic Barre <ludovic.barre@st.com>
Signed-off-by: NAlexandre Torgue <alexandre.torgue@st.com>