Revert "Upgrade to int64_t to avoid out-of-range"

This reverts commit 9395b34e2088fa266232e6fa8c7dfe63bb064254, because it
did not have any effect in eliminate ubsan warnings as intended.

Change-Id: I9221385217f062a0356fe0c68643b12751048f69

av1/encoder/mcomp.c

diff --git a/av1/encoder/mcomp.c b/av1/encoder/mcomp.c
index f6366eb..d069eef 100644
--- a/av1/encoder/mcomp.c
+++ b/av1/encoder/mcomp.c
@@ -90,8 +90,7 @@
 int av1_mv_bit_cost(const MV *mv, const MV *ref, const int *mvjcost,
                     int *mvcost[2], int weight) {
   const MV diff = { mv->row - ref->row, mv->col - ref->col };
-  return (int)ROUND_POWER_OF_TWO(
-      (int64_t)mv_cost(&diff, mvjcost, mvcost) * weight, 7);
+  return ROUND_POWER_OF_TWO(mv_cost(&diff, mvjcost, mvcost) * weight, 7);
 }
 
 #define PIXEL_TRANSFORM_ERROR_SCALE 4
@@ -110,8 +109,8 @@
 static int mvsad_err_cost(const MACROBLOCK *x, const MV *mv, const MV *ref,
                           int sad_per_bit) {
   const MV diff = { (mv->row - ref->row) * 8, (mv->col - ref->col) * 8 };
-  return (int)ROUND_POWER_OF_TWO(
-      (int64_t)mv_cost(&diff, x->nmvjointsadcost, x->mvsadcost) * sad_per_bit,
+  return ROUND_POWER_OF_TWO(
+      (unsigned)mv_cost(&diff, x->nmvjointsadcost, x->mvsadcost) * sad_per_bit,
       AV1_PROB_COST_SHIFT);
 }