selftests: print installation complete message

Add installation complete message to Makefile install logic.

Link: https://lore.kernel.org/r/20250703231747.37544-1-skhan@linuxfoundation.org
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: shuahkh

tools/testing/selftests/Makefile

@@ -300,6 +300,7 @@ ifdef INSTALL_PATH
 	else \
 		printf "Unable to get version from git describe\n"; \
 	fi
+	@echo "**Kselftest Installation is complete: $(INSTALL_PATH)**"
 else
 	$(error Error: set INSTALL_PATH to use install)
 endif