Clean up SGR code and make consistent

Change-Id: I99c0cd287d154acc5063c92eb3ad4035bff8dad7

av1/encoder/bitstream.c

diff --git a/av1/encoder/bitstream.c b/av1/encoder/bitstream.c
index 21e23ea..99dd67a 100644
--- a/av1/encoder/bitstream.c
+++ b/av1/encoder/bitstream.c
@@ -2194,13 +2194,13 @@
   aom_write_literal(wb, sgrproj_info->ep, SGRPROJ_PARAMS_BITS);
   const sgr_params_type *params = &sgr_params[sgrproj_info->ep];
 
-  if (params->r1 == 0) {
+  if (params->r0 == 0) {
     assert(sgrproj_info->xqd[0] == 0);
     aom_write_primitive_refsubexpfin(
         wb, SGRPROJ_PRJ_MAX1 - SGRPROJ_PRJ_MIN1 + 1, SGRPROJ_PRJ_SUBEXP_K,
         ref_sgrproj_info->xqd[1] - SGRPROJ_PRJ_MIN1,
         sgrproj_info->xqd[1] - SGRPROJ_PRJ_MIN1);
-  } else if (params->r2 == 0) {
+  } else if (params->r1 == 0) {
     aom_write_primitive_refsubexpfin(
         wb, SGRPROJ_PRJ_MAX0 - SGRPROJ_PRJ_MIN0 + 1, SGRPROJ_PRJ_SUBEXP_K,
         ref_sgrproj_info->xqd[0] - SGRPROJ_PRJ_MIN0,