gallivm/nir: split tex/sampler indirect offsets

gallivm/nir: split tex/sampler indirect offsets

vulkan has these separate, should be fine for GL as well as
the values will be the same anyways.

Fixes:
dEQP-VK.binding_model.shader_access.secondary_cmd_buf.uniform_texel_buffer.*
dEQP-VK.binding_model.descriptorset_random.sets4.noarray.ubolimitlow.sbolimitlow.sampledimglow.outimgtexlow.noiub.uab.vert.noia*
dEQP-VK.binding_model.descriptor_copy.graphics.uniform_texel_buffer.*

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6339>