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_ar933x.c b/drivers/serial/serial_ar933x.c
index 897ea5d..382c3b3 100644
--- a/drivers/serial/serial_ar933x.c
+++ b/drivers/serial/serial_ar933x.c
@@ -13,6 +13,7 @@
 #include <asm/addrspace.h>
 #include <asm/types.h>
 #include <dm/pinctrl.h>
+#include <linux/bitops.h>
 #include <mach/ar71xx_regs.h>
 
 #define AR933X_UART_DATA_REG            0x00