slim-msm: Optimize QMI response timeout

For a Slimbus transaction through QMI, timeout
if there is no response within 500ms and return
timeout to the slimbus client.
Transactions through QMI will complete within milli
seconds. So it is better to timeout for 500ms
instead of 5 seconds.

Change-Id: I818b7c6ff7941d183e1975b21a092f37a0d94264
Signed-off-by: Dilip Kota <dkota@codeaurora.org>