binderfs: remove unused INTSTRLEN macro

Fix the following W=1 build error:

drivers/android/binderfs.c:42: error: macro "INTSTRLEN" is not used [-Werror=unused-macros]
   42 | #define INTSTRLEN 21
      |

No functional changes in this patch.

Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20220829201254.1814484-8-cmllamas@google.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>