workloads/deepbench: lengthen timeout
workloads/deepbench: lengthen timeout

Lengthen timeout for gemm and conv tests to be the same as for sparse
test. While the former two usually take a lot less time, their execution
time will vary significantly depending on the target and the runtime
environment (e.g. cpu frequencies might be forced to lowest values).

ARM-software/workload-automation,setrofim/workload-automation,setrofim/workload-automation,ARM-software/workload-automation,setrofim/workload-automation,ARM-software/workload-automation,lisatn/workload-automation,ARM-software/workload-automation,lisatn/workload-automation,setrofim/workload-automation,lisatn/workload-automation,lisatn/workload-automation