staging: mfd: hi6421-spmi-pmic: fix error return code in hi6421_spmi_pmic_probe()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: 4524ac56 ("staging: mfd: add a PMIC driver for HiSilicon 6421 SPMI version")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Link: https://lore.kernel.org/r/20201118103724.57451-1-wanghai38@huawei.com


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