Remove "Settings" option from menu entry.

This gallery application does not implement at this time
any configurable setting, so disable the menu entry
since it does not do anything anyway.

Category: Aosp-app
Upstream-Candidate: no
Issue: APDEV-2660
Change-Id: Ie67ffbe197952f2c4577edc42fe544d1916fb8eb
Signed-off-by: Adriana Reus <adriana.reus@intel.com>
Reviewed-on: https://android.intel.com/177726
Reviewed-by: Vlaescu, CristianX <cristianx.vlaescu@intel.com>
Tested-by: Vlaescu, CristianX <cristianx.vlaescu@intel.com>
Reviewed-by: Suman, Viorel <viorel.suman@intel.com>
Reviewed-by: Breana, Tiberiu A <tiberiu.a.breana@intel.com>
Reviewed-by: Chiras, Robert <robert.chiras@intel.com>