etnaviv: call nir_lower_bool_to_bitsize

etnaviv: call nir_lower_bool_to_bitsize

Starting with commit 6f394343b1f ("nir/algebraic: i2f(f2i()) -> trunc()")
dEQP-GLES2.functional.shaders.operator.binary_operator.div.lowp_int_vertex
ends with an unsuppored flt instruction. Use nir_lower_bool_to_bitsize to
convert this flt to a flt32 which is supported. This fixes the introduced
regression.

Cc: 20.2 <mesa-stable@lists.freedesktop.org>
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6182>