r300g: Remove extra printf format specifiers.

r300g: Remove extra printf format specifiers.

Fix warning reported by Coverity Scan.
Missing argument to printf format specifier (PRINTF_ARGS)
missing_argument: No argument for format specifier %s.

Fixes: 04c1536bf7ab ("r300g: rasterizer debug logging")
Fixes: 85efb2fff0d4 ("r300g: try to use color varyings for texcoords if max texcoord limit is exceeded")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5274>