Remove redundant checks in av1_compute_global_motion_disflow

Remove duplicate image dimension and corner count checks in
av1_compute_global_motion_disflow() that were inadvertently added
during a merge conflict resolution.

Coverity-defect: CID 564107 (Logically dead code)
Change-Id: I35b0acfdea4d4802f0cdeaae8f22d24c2fd9df4e

aom_dsp/flow_estimation/disflow.c

diff --git a/aom_dsp/flow_estimation/disflow.c b/aom_dsp/flow_estimation/disflow.c
index 6a41642..cb044ba 100644
--- a/aom_dsp/flow_estimation/disflow.c
+++ b/aom_dsp/flow_estimation/disflow.c
@@ -808,13 +808,6 @@
       ref_pyramid->layers[0].height != src_height) {
     return false;
   }
-  if (src_width < (1 << DOWNSAMPLE_SHIFT) ||
-      src_height < (1 << DOWNSAMPLE_SHIFT)) {
-    return false;
-  }
-  if (src_corners->num_corners == 0) {
-    return false;
-  }
 
   if (ref_pyramid->layers[0].stride != src_pyramid->layers[0].stride) {
     return false;