habanalabs/gaudi: fix warning: var might be used uninitialized

kernel test robot:
"warning: variable 'index' is used uninitialized whenever 'if' condition
is false"

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Koby Elbaz <kelbaz@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>