Add spinlock protection on IPCC register update to avoid race condition.
Without this fix, stm32_ipcc_set_bits and stm32_ipcc_clr_bits can be
called in parallel for different channels. This results in register
corruptions.
Signed-off-by: NArnaud Pouliquen <arnaud.pouliquen@st.com>
Reviewed-by: NFabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: NJassi Brar <jaswinder.singh@linaro.org>