soc: qcom: glink: Return error in case of invalid input

In case of invalid input, fifo_read() function is returning
success instead of error. The patch returns error properly in
case of invalid input.

Change-Id: I6e3903381ef7ec8d0dd536623d10213460d0ae8e
Signed-off-by: Hardik Arya <harya@codeaurora.org>