drm/tegra: hdmi: Open-code drm_simple_encoder_init()

drm/tegra: hdmi: Open-code drm_simple_encoder_init()

The helper drm_simple_encoder_init() is a trivial wrapper around
drm_encoder_init() that only provides a static drm_encoder_funcs with
.destroy set to drm_encoder_cleanup(). Open-code the initialization
with a driver-specific instance of drm_encoder_funcs and remove the
dependency on drm_simple_kms_helper.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Souradipto Das <souradiptodas6@gmail.com>
[treding@nvidia.com: fix issues flagged by checkpatch]
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patch.msgid.link/20260513100501.6468-1-souradiptodas6@gmail.com