UPSTREAM: linux/bitfield.h: import <linux/bitfield.h> from Linux 4.13

Copied from Linux 4.13.

Commit log of 3e9b3112ec74 of Linux explains well why this header
is useful.

Change-Id: I6d565317c573e

UPSTREAM: linux/bitfield.h: import <linux/bitfield.h> from Linux 4.13

Copied from Linux 4.13.

Commit log of 3e9b3112ec74 of Linux explains well why this header
is useful.

Change-Id: I6d565317c573e01eb5df2af5a24982db049e8e08
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
(cherry picked from commit 6990e91f0971b877cd636e646f93587b1afbb284)

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