stm32f7: enable fsmc

This uses the existing f4 code as a new shared common base code.

lib/stm32/f4/Makefile

@@ -49,7 +49,7 @@ OBJS		+= dma_common_f24.o
 OBJS		+= exti_common_all.o 
 OBJS		+= flash.o flash_common_all.o flash_common_f.o flash_common_f24.o
 OBJS		+= flash_common_idcache.o
-OBJS		+= fmc.o
+OBJS		+= fmc_common_f47.o
 OBJS		+= gpio_common_all.o gpio_common_f0234.o gpio.o
 OBJS		+= hash_common_f24.o
 OBJS		+= i2c_common_v1.o