misc: bcm-vk: Fix a couple error codes in probe()

These errors should return negative error codes instead of returning
success.

Fixes: 064ffc7c ("misc: bcm-vk: add autoload support")
Fixes: 522f6926 ("misc: bcm-vk: add Broadcom VK driver")
Acked-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YBpyEbmz00rjvT9S@mwanda


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>