intel/dump_gpu: add missing gdb option

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>

src/intel/tools/intel_dump_gpu.in

@@ -8,6 +8,8 @@ Usage: intel_dump_gpu [OPTION]... [--] COMMAND ARGUMENTS
 Run COMMAND with ARGUMENTS and dump an AUB file that captures buffer
 contents and execution of the GEM application.
 
+  -g, --gdb          Launch GDB
+
   -o, --output=FILE  Name of AUB file. Defaults to COMMAND.aub
 
       --device=ID    Override PCI ID of the reported device