clk: stm32f7: rename clk_stm32f7.c to clk_stm32f.c

Now that clk_stm32f7.c manages clocks for both STM32F4 and F7 SoCs
rename it to a more generic clk_stm32f.c

Fix also some checkpatch errors/warnings.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Vikas Manocha <vikas.manocha@st.com>
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 83fe88c..bcc8f82 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -21,5 +21,5 @@
 obj-$(CONFIG_CLK_BCM6345) += clk_bcm6345.o
 obj-$(CONFIG_CLK_BOSTON) += clk_boston.o
 obj-$(CONFIG_ARCH_ASPEED) += aspeed/
-obj-$(CONFIG_STM32F7) += clk_stm32f7.o
+obj-$(CONFIG_CLK_STM32F) += clk_stm32f.o
 obj-$(CONFIG_STM32H7) += clk_stm32h7.o