net: ipa: change GSI command timeout

The GSI command timeout is currently 5 seconds, which is much higher
than it should be.

Express the timeout in milliseconds rather than seconds, and reduce
it to 50 milliseconds.

Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>