pch_phub: fix error return code in pch_phub_probe()

Error code had been assigned to retval in some error handling case
but never use it, 0 is always returned in those case, this patch
fix them to return a negative error code.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>