scsi: ufs: core: Fix invalid probe error return value

In the Linux kernel, the following vulnerability has been resolved:

scsi: ufs: core: Fix invalid probe error return value

After DME Link Startup, the error return value is set to the MIPI UniPro
GenericErrorCode which can be 0 (SUCCESS) or 1 (FAILURE). Upon failure
during driver probe, the error code 1 is propagated back to the driver
probe function which must return a negative value to indicate an error,
but 1 is not negative, so the probe is considered to be successful even
though it failed. Subsequently, removing the driver results in an oops
because it is not in a valid state.

This happens because none of the callers of ufshcd_init() expect a
non-negative error code.

Fix the return value and documentation to match actual usage.