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/arch/mips/mach-ath79/ar934x/ddr.c b/arch/mips/mach-ath79/ar934x/ddr.c
index 9c5a6b6..218f60a 100644
--- a/arch/mips/mach-ath79/ar934x/ddr.c
+++ b/arch/mips/mach-ath79/ar934x/ddr.c
@@ -9,6 +9,7 @@
 #include <asm/io.h>
 #include <asm/addrspace.h>
 #include <asm/types.h>
+#include <linux/bitops.h>
 #include <linux/delay.h>
 #include <mach/ar71xx_regs.h>
 #include <mach/ath79.h>