drm/file: Don't set master on in-kernel clients

It only makes sense for userspace clients.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180618141739.48151-3-noralf@tronnes.org


Patch-mainline: 20180618141739.48151-3-noralf@tronnes.org @ 18/06/18, 02:17 p.m.
[stalek@codeaurora.org: initialize return variable to fix compilation issue.].

Change-Id: Ic2cad4c5e42fb9daf362945d4f20ead3b78b4d8a
Signed-off-by: Shubham Talekar <stalek@codeaurora.org>