Add gdsp_remoteproc test script and README for Lemans platform

This commit introduces a test script to validate gpdsp0 and gpdsp1 remoteproc functionality on the Lemans platform. It includes start/stop/restart checks and logs results in a standardized format. A detailed README is also added to document usage, expected output, and prerequisites.

Signed-off-by: Sai-teja573 <122cs0573@nitrkl.ac.in>

Author: Sai-teja573