broadcom/vc5: Fix up the NIR types of FS outputs generated by NIR-to-TGSI.

broadcom/vc5: Fix up the NIR types of FS outputs generated by NIR-to-TGSI.

Unfortunately TGSI doesn't record the type of the FS output like GLSL
does, but VC5's TLB writes depend on the output's base type.  Just record
the type in the key at variant compile time when we've got a TGSI input
and then fix it up.

Fixes KHR-GLES3.packed_pixels.pbo_rectangle.rgba32i/ui and apparently a
GPU hang that breaks most tests that come after it.