spi: bcmbca-hsspi: Fix error code in probe() function

This code accidentally returns success instead of a negative error code.

Fixes: a38a2233 ("spi: bcmbca-hsspi: Add driver for newer HSSPI controller")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: William Zhang <william.zhang@broadcom.com>
Link: https://lore.kernel.org/r/Y+zmrNJ9zjNQpzWq@kili


Signed-off-by: Mark Brown <broonie@kernel.org>