intel: fix leaking memory on shader creation
ralloc_adopt takes care of all the shader's children, but shader itsel ends up orphaned and never gets free'd.
Fixes: ef5bce92 ("intel: Drop the last uses of a mem_ctx in nir_builder_init_simple_shader().") Closes: #4951 (closed)
Signed-off-by: Yevhenii Kolesnikov yevhenii.kolesnikov@globallogic.com