drm/bridge: samsung-dsim: check the return value only if necessary

It was useless to check again the "ret" variable if the function
register_host() was not called.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231207161056.183442-1-dario.binacchi@amarulasolutions.com