ti_sci: Provide error code on error exit

ti_sci: Provide error code on error exit

In ti_sci_get_response the check for message sequence will return ret
on a fail but ret will be 0 at that point. Instead return -EINVAL.
Also change dev_dbg call to dev_err to be consistent with other error
detection code in the same function.

This issue was found by Smatch.

Reviewed-by: Udit Kumar <u-kumar1@ti.com>
Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>
Reviewed-by: Nishanth Menon <nm@ti.com>
Tested-by: Anshul Dalal <anshuld@ti.com>