aco: allow direct_fetch=true for vec4 VS input loads

aco: allow direct_fetch=true for vec4 VS input loads

This seems to be a (mostly harmless) mistake from 369b8cffea2.

fossil-db (navi21):
Totals from 15 (0.01% of 135636) affected shaders:
Instrs: 1992 -> 1999 (+0.35%)
Latency: 13557 -> 13567 (+0.07%); split: -0.24%, +0.31%
InvThroughput: 4059 -> 4065 (+0.15%); split: -0.20%, +0.34%
Copies: 186 -> 193 (+3.76%)

fossil-db (polaris10):
Totals from 5 (0.00% of 135610) affected shaders:

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18225>