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/drivers/serial/serial_sti_asc.c b/drivers/serial/serial_sti_asc.c
index 27d3ec9..5fbbfac 100644
--- a/drivers/serial/serial_sti_asc.c
+++ b/drivers/serial/serial_sti_asc.c
@@ -11,6 +11,7 @@
 #include <log.h>
 #include <serial.h>
 #include <asm/io.h>
+#include <linux/bitops.h>
 
 DECLARE_GLOBAL_DATA_PTR;