pcspk_init() is a legacy init function, inline and remove it.

Since the device is realized using &error_fatal, use the same
error for setting the "pit" link.

Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20231019073307.99608-1-philmd@linaro.org>