drm/amd/display: Use devm_i2c_add_adapter to simplify i2c cleanup logic

drm/amd/display: Use devm_i2c_add_adapter to simplify i2c cleanup logic

This commit replaces the utilization of i2c_add/del_adapter() with
devm_i2c_add_adapter() to reduce the amount of boilerplate. Using
devm_i2c_add_adapter() has the advantage of removing the manual
manipulation of the I2C adapter.

Suggested-by: Robert Beckett <bob.beckett@collabora.com>
Signed-off-by: Rodrigo Siqueira <siqueira@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>