r300: there is no limitation on presubtract source file

r300: there is no limitation on presubtract source file

RV530 shader-db:
total instructions in shared programs: 128840 -> 128803 (-0.03%)
instructions in affected programs: 1085 -> 1048 (-3.41%)
helped: 37
HURT: 1
total presub in shared programs: 7670 -> 7751 (1.06%)
presub in affected programs: 328 -> 409 (24.70%)
helped: 0
HURT: 81
total temps in shared programs: 16926 -> 16939 (0.08%)
temps in affected programs: 182 -> 195 (7.14%)
helped: 6
HURT: 19
total cycles in shared programs: 193751 -> 193729 (-0.01%)
cycles in affected programs: 3088 -> 3066 (-0.71%)
helped: 33
HURT: 5

Reviewed-by: Filip Gawin <filip.gawin@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24830>