drm/lima: fix lima_gem_wait() return value

drm_gem_reservation_object_wait() returns 0 if it succeeds and -ETIME
if it timeouts, but lima driver assumed that 0 is error.

Cc: stable@vger.kernel.org
Fixes: a1d2a633

 ("drm/lima: driver for ARM Mali4xx GPUs")
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190908024800.23229-1-anarsoul@gmail.com