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/net/net.c b/net/net.c
index 0352935..3793291 100644
--- a/net/net.c
+++ b/net/net.c
@@ -95,6 +95,7 @@
 #include <env_internal.h>
 #include <errno.h>
 #include <image.h>
+#include <log.h>
 #include <net.h>
 #include <net/fastboot.h>
 #include <net/tftp.h>