freedreno/ir3: remove store_output lowered to store_shared_ir3

freedreno/ir3: remove store_output lowered to store_shared_ir3

Fixes crashes that were unnoticed in CI because debug_assert() was not
enabled (but become real crashes after the next patch):

dEQP-GLES31.functional.shaders.builtin_functions.integer.bitfieldextract.ivec2_highp_geometry
dEQP-GLES31.functional.shaders.builtin_functions.integer.bitfieldextract.ivec2_lowp_geometry
dEQP-GLES31.functional.shaders.builtin_functions.integer.bitfieldextract.ivec2_mediump_geometry
dEQP-GLES31.functional.shaders.builtin_functions.integer.bitfieldextract.uvec2_highp_geometry
dEQP-GLES31.functional.shaders.builtin_functions.integer.bitfieldextract.uvec2_lowp_geometry
dEQP-GLES31.functional.shaders.builtin_functions.integer.bitfieldextract.uvec2_mediump_geometry

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>