mockib/counters: address CodeQL Atoi -> uint16 truncation warning #424

Job	Run time
basic / variables / variables	1m 56s
basic / golang / check	4m 52s
basic / code-scanning / Analyze Go code with CodeQL	3m 17s
nvml-mock-e2e / e2e-multi-node	3m 56s
nvml-mock-e2e / ibping-multinode	3m 21s
nvml-mock-e2e / e2e-device-plugin (h100)	3m 9s
nvml-mock-e2e / e2e-dra (a100)	3m 44s
nvml-mock-e2e / e2e-gpu-operator (h100)	3m 56s
nvml-mock-e2e / e2e-device-plugin (a100)	3m 6s
nvml-mock-e2e / e2e-gpu-operator (a100)	4m 13s
nvml-mock-e2e / e2e-dra (h100)	3m 4s
nvml-mock-e2e / e2e-dra (t4)	3m 21s
nvml-mock-e2e / e2e-device-plugin (t4)	3m 7s
nvml-mock-e2e / e2e-gpu-operator (t4)	3m 55s
	48m 57s

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