selftests/drivers/gpu: Add error messages to drm_mm.sh

Add error messages when the module test-drm_mm is not found or could
not be removed to make tests output more readable.

Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/drivers/gpu/drm_mm.sh

@@ -3,14 +3,14 @@
 # Runs API tests for struct drm_mm (DRM range manager)
 
 if ! /sbin/modprobe -n -q test-drm_mm; then
-       echo "drivers/gpu/drm_mm: [skip]"
+       echo "drivers/gpu/drm_mm: module test-drm_mm is not found in /lib/modules/`uname -r` [skip]"
        exit 77
 fi
 
 if /sbin/modprobe -q test-drm_mm; then
        /sbin/modprobe -q -r test-drm_mm
        echo "drivers/gpu/drm_mm: ok"
 else
-       echo "drivers/gpu/drm_mm: [FAIL]"
+       echo "drivers/gpu/drm_mm: module test-drm_mm could not be removed [FAIL]"
        exit 1
 fi