firmware: arm_scmi: increase the response timeout

For synchronous messages sent from the agent to platform,
agent waits for response for 30 milli seconds (max_rx_timeout)
before timing out if response gets delayed from platform.

Increase the timeout value to 1 second to minimize message
send failures in case of delays.

Change-Id: I72e9ab33a9be675b64301e904e8d43fb8bb89e50
Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>