tgsi: reduce tgsi_opcode_info::pre_dedent and post_indent to 1 bit

It's not clear why they were ever 2 bits to begin with. Perhaps
the original intent was to use signed values, but that doesn't
seem to have ever been the case in master.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/gallium/auxiliary/tgsi/tgsi_info.h

@@ -76,8 +76,8 @@ struct tgsi_opcode_info
    unsigned is_tex:1;
    unsigned is_store:1;
    unsigned is_branch:1;
-   int pre_dedent:2;
-   int post_indent:2;
+   unsigned pre_dedent:1;
+   unsigned post_indent:1;
    enum tgsi_output_mode output_mode:3;
    const char *mnemonic;
    uint opcode;