intel: Rename Genx keyword to Gfxx

Commands used to do the changes:
export SEARCH_PATH="src/intel src/gallium/drivers/iris src/mesa/drivers/dri/i965"
grep -E "Gen[[:digit:]]+" -rIl $SEARCH_PATH | xargs sed -ie "s/Gen\([[:digit:]]\+\)/Gfx\1/g"

Exclude changes in src/intel/perf/oa-*.xml:
find src/intel/perf -type f \( -name "*.xml" \) | xargs sed -ie "s/Gfx/Gen/g"

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9936>

src/intel/compiler/brw_fs_builder.h

@@ -703,7 +703,7 @@ namespace brw {
       }
 
       /**
-       * Gen4 predicated IF.
+       * Gfx4 predicated IF.
        */
       instruction *
       IF(brw_predicate predicate) const
@@ -849,10 +849,10 @@ namespace brw {
           * expanding that result out, but we would need to be careful with
           * masking.
           *
-          * Gen6 hardware ignores source modifiers (negate and abs) on math
+          * Gfx6 hardware ignores source modifiers (negate and abs) on math
           * instructions, so we also move to a temp to set those up.
           *
-          * Gen7 relaxes most of the above restrictions, but still can't use IMM
+          * Gfx7 relaxes most of the above restrictions, but still can't use IMM
           * operands to math
           */
          if ((shader->devinfo->ver == 6 &&