stm32: stm32f4: move flash driver to mtd driver location

Same flash driver can be used by other stm32 families like stm32f7.
Better place for this driver would be mtd driver location.

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
diff --git a/arch/arm/mach-stm32/stm32f4/Makefile b/arch/arm/mach-stm32/stm32f4/Makefile
index 42d01db..020e783 100644
--- a/arch/arm/mach-stm32/stm32f4/Makefile
+++ b/arch/arm/mach-stm32/stm32f4/Makefile
@@ -8,4 +8,4 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-obj-y += soc.o clock.o timer.o flash.o
+obj-y += soc.o clock.o timer.o