drivers: reset: Add STM32 reset driver

The STM32 MCUs family IPs can be reset by accessing some registers
from the RCC block.

The list of available reset lines is documented in the DT bindings.

Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>