Nvidia no sensor data

On the nvidia driver version 525.89.02 the nvidia-smi --query returns the output not line per line instead the output is returned in a single line containing the '\n' in the read QString. So splitting the input on the line break character seems to fix the query result.

This fixes also my issue that the GPU usage and Temperature is always 0 because the of the failing query the m_index of the NvidiaSmiProcess class stucks still in the default state of -1. So the results of the nvidia-smi dmon process wasn't forwarded.