drm/simpledrm: Remove !fb check from atomic_update

commit 6156c5fd928d6cf6f0a557a2be117a1733e96601 from
https://nv-tegra.nvidia.com/r/3rdparty/canonical/linux-jammy.git

 jetson_36.3

The primary plane implements atomic_disable, so atomic_update will
not be called without a framebuffer set. Remove the test for !fb.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220922130944.27138-4-tzimmermann@suse.de


(cherry picked from commit 7fcf1930)
Change-Id: Ia79855cc7eb2c79c6deb0546c7acc97fe14b889e
Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/3rdparty/canonical/linux-jammy/+/2985859


Reviewed-by: svcacv <svcacv@nvidia.com>
Reviewed-by: Jonathan Hunter <jonathanh@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>
Signed-off-by: Rajeshkumar Ramasamy <rajeshkumar.ramasamy@windriver.com>