Gallery: FilterShowActivity: Fix loading spinner being show forever

69cf0d8 was pulled from an 8998 branch. 8998 will feature a dual camera
setup, so that patch didn't keep in mind that the commit can be used on
devices without it. stopLoadingIndicator() is only called when the
parseDepthMap asyncTask is executed. This task is only executed if the
device supports dual camera. Dismiss the spinner if it does not.

Change-Id: I1b3cab2da1dc7371c81b0e5328dd959eda770c28
Signed-off-by: Alex Naidis <alex.naidis@linux.com>