clk: Add directory for STM32 clock drivers

Add a directory in drivers/clk to regroup the clock drivers for all
STM32 Soc with CONFIG_ARCH_STM32 (MCUs with cortex M) or
CONFIG_ARCH_STM32MP (MPUs with cortex A).

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Grzegorz Szymaszek <gszymaszek@short.pl>
Acked-by: Sean Anderson <seanga2@gmail.com>
Change-Id: I955af307963f732167396f0157a30cf2fc91f150
diff --git a/drivers/clk/stm32/Makefile b/drivers/clk/stm32/Makefile
new file mode 100644
index 0000000..f66f295
--- /dev/null
+++ b/drivers/clk/stm32/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Copyright (C) 2022, STMicroelectronics - All Rights Reserved
+
+obj-$(CONFIG_CLK_STM32F) += clk-stm32f.o
+obj-$(CONFIG_CLK_STM32H7) += clk-stm32h7.o
+obj-$(CONFIG_CLK_STM32MP1) += clk-stm32mp1.o