drivers: Remove board.h include

We either don't need board.h in the driver or we should be include soc.h
instead.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>
diff --git a/drivers/spi/spi_ll_stm32.c b/drivers/spi/spi_ll_stm32.c
index ed7fda9..8290297 100644
--- a/drivers/spi/spi_ll_stm32.c
+++ b/drivers/spi/spi_ll_stm32.c
@@ -10,7 +10,7 @@
 
 #include <misc/util.h>
 #include <kernel.h>
-#include <board.h>
+#include <soc.h>
 #include <errno.h>
 #include <spi.h>
 #include <toolchain.h>