common: Drop log.h from common header

Move this header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c
index ee44973..635955e 100644
--- a/drivers/spi/mxs_spi.c
+++ b/drivers/spi/mxs_spi.c
@@ -14,6 +14,7 @@
 
 #include <common.h>
 #include <cpu_func.h>
+#include <log.h>
 #include <malloc.h>
 #include <memalign.h>
 #include <spi.h>