hwspinlock: add STM32 hwspinlock device

This patch adds support of hardware semaphores for stm32mp1 SoC.
The hardware block provides 32 semaphores.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>