linux/bitops.h: GENMASK copy from linux

GENMASK is used to create a contiguous bitmask([hi:lo]).

This patch is a copy from Linux, with below commit details
"bitops: Fix shift overflow in GENMASK macros"
(sha1: 00b4d9a14125f1e51874def2b9de6092e007412d)

Cc: Tom Rini <trini@konsulko.com>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Jagan Teki <jteki@openedev.com>
diff --git a/include/asm-generic/bitsperlong.h b/include/asm-generic/bitsperlong.h
new file mode 100644
index 0000000..75ee21e8
--- /dev/null
+++ b/include/asm-generic/bitsperlong.h
@@ -0,0 +1,8 @@
+#ifndef __ASM_GENERIC_BITS_PER_LONG
+#define __ASM_GENERIC_BITS_PER_LONG
+
+#ifndef BITS_PER_LONG_LONG
+#define BITS_PER_LONG_LONG 64
+#endif
+
+#endif /* __ASM_GENERIC_BITS_PER_LONG */