drm/msm/mdp5: Fix mdp5_cfg_init error return

drm/msm/mdp5: Fix mdp5_cfg_init error return

BugLink: https://bugs.launchpad.net/bugs/1863019
[ Upstream commit fc19cbb785d7bbd1a1af26229b5240a3ab332744 ]

If mdp5_cfg_init fails because of an unknown major version, a null pointer
dereference occurs.  This is because the caller of init expects error
pointers, but init returns NULL on error.  Fix this by returning the
expected values on error.

Fixes: 2e362e1772b8 (drm/msm/mdp5: introduce mdp5_cfg module)
Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>