mailbox: introduce stm32-ipcc driver

On STM32 family, the IPCC peripheral allows the communication
between 2 processors offering doorbells mechanism.

Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Signed-off-by: Loic Pallardy <loic.pallardy@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 2836ee4..11bf552 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -24,6 +24,13 @@
 	  This enables support for the NVIDIA Tegra HSP Hw module, which
 	  implements doorbells, mailboxes, semaphores, and shared interrupts.
 
+config STM32_IPCC
+	bool "Enable STM32 IPCC controller support"
+	depends on DM_MAILBOX && ARCH_STM32MP
+	help
+	  This enables support for the STM32MP IPCC Hw module, which
+	  implements doorbells between 2 processors.
+
 config K3_SEC_PROXY
 	bool "Texas Instruments K3 Secure Proxy Driver"
 	depends on DM_MAILBOX && ARCH_K3