common: Drop linux/bitops.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/toradex/colibri_imx6/colibri_imx6.c b/board/toradex/colibri_imx6/colibri_imx6.c
index bdb4ac6..6522af4 100644
--- a/board/toradex/colibri_imx6/colibri_imx6.c
+++ b/board/toradex/colibri_imx6/colibri_imx6.c
@@ -12,6 +12,7 @@
 #include <env.h>
 #include <init.h>
 #include <net.h>
+#include <linux/bitops.h>
 #include <linux/delay.h>
 
 #include <asm/arch/clock.h>