glsl/mesa: stop duplicating geom and tcs layout values

glsl/mesa: stop duplicating geom and tcs layout values

We already store these in gl_shader and gl_program here we
remove it from gl_shader_program and just use the values
from gl_shader.

This will allow us to keep the shader cache restore code as
simple as it can be while making it somewhat clearer where these
values originate from.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>