stm32f7: use spi v2 peripheral.

F7 indeed has v2 peripheral, not the v1.  Distinguishing figure is the
8/16bit fifo.

lib/stm32/f7/Makefile

@@ -50,7 +50,7 @@ OBJS		+= pwr.o rcc.o
 
 OBJS		+= rcc_common_all.o
 OBJS		+= rng_common_v1.o
-OBJS		+= spi_common_all.o spi_common_v1.o spi_common_v1_frf.o
+OBJS		+= spi_common_all.o spi_common_v2.o
 OBJS		+= timer_common_all.o
 OBJS		+= usart_common_all.o usart_common_v2.o