pcd: fix error codes in pcd_init_unit()

Return -ENODEV on these error paths instead of returning success.

Fixes: af761f27 ("pcd: cleanup initialization")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20211001122623.GA2283@kili


Signed-off-by: Jens Axboe <axboe@kernel.dk>