Do not skip GLOBALMV mode when GM is disabled

GLOBALMV falls back to zero MV mode when Global Motion is disabled.

Change-Id: I47ce6bdfa553303b109ace3490deac3848617d16

av1/encoder/rdopt.c

diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index 224ee12..5828cb5 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -11924,11 +11924,6 @@
     return 2;
   }
 
-  if (!cpi->oxcf.enable_global_motion &&
-      (this_mode == GLOBALMV || this_mode == GLOBAL_GLOBALMV)) {
-    return 1;
-  }
-
   if (!cpi->oxcf.enable_onesided_comp && comp_pred && cpi->all_one_sided_refs) {
     return 1;
   }