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>