Don't try to set service.bootanim.exit

init has never allowed the bootanimation code to
set service.bootanim.exit, and has always generated the
dmesg error message

  <3>[   17.644615] init: sys_prop: permission denied uid:1003  name:service.bootanim.exit

Since setting this property has no effect and never worked, delete
the code which tries to do it.

Change-Id: Idacc5467d85479a8cf974702af8895011be585ea

cmds/bootanimation/BootAnimation.cpp

@@ -307,9 +307,6 @@ bool BootAnimation::threadLoop()
         r = movie();
     }
 
-    // No need to force exit anymore
-    property_set(EXIT_PROP_NAME, "0");
-
     eglMakeCurrent(mDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
     eglDestroyContext(mDisplay, mContext);
     eglDestroySurface(mDisplay, mSurface);