etnaviv: add gpu_supports_texture_target(..)

etnaviv: add gpu_supports_texture_target(..)

Currently I am seeing a handful of the following debug message:
translate_texture_target:495: Unhandled texture target: 0

PIPE_BUFFER is not handled in translate_texture_target(..) which makes
sense as it is used to translate from PIPE_XXX to GPU specific value
during etna_create_sampler_view_state(..).

To fix this problem introduce gpu_supports_texture_target(..) which just
checks if the texture target is supported.

Fixes: dfe048058fa ("etnaviv: support 3D and 2D array textures")
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Jonathan Marek <jonathan@marek.ca>