drivers: thermal: virtual-sensor: Add new virtual sensor for QCS405

Add new virtual sensor definition for cpuss-max-step for QCS405.
This virtual sensor can be used to monitor the overall temperature
of CPU cluster device.

Change-Id: I4dd4362bec5e1120953610da27291f5edf572bc0
Signed-off-by: Manaf Meethalavalappu Pallikunhi <manafm@codeaurora.org>