radeonsi: release tokens after creating the shader program

radeonsi: release tokens after creating the shader program

ureg_get_tokens clears the reference to the tokens, and create_compute_state makes
a copy, hence the tokens must be explicitely released.

Fixes: Direct leak of 256 byte(s) in 1 object(s) allocated from:
    #0 0x7ff729cf3c60 in realloc (/usr/lib64/gcc/x86_64-pc-linux-gnu/7.3.0/libasan.so+0xdbc60)
    #1 0x7ff721b1240c in tokens_expand ../../samba/mesa/src/gallium/auxiliary/tgsi/tgsi_ureg.c:234
    #2 0x7ff721b1c9c0 in get_tokens ../../samba/mesa/src/gallium/auxiliary/tgsi/tgsi_ureg.c:257
    #3 0x7ff721b1c9c0 in copy_instructions ../../samba/mesa/src/gallium/auxiliary/tgsi/tgsi_ureg.c:2040
    #4 0x7ff721b1c9c0 in ureg_finalize ../../samba/mesa/src/gallium/auxiliary/tgsi/tgsi_ureg.c:2090
    #5 0x7ff721b1e919 in ureg_get_tokens ../../samba/mesa/src/gallium/auxiliary/tgsi/tgsi_ureg.c:2167
    #6 0x7ff721f8b35a in si_create_dma_compute_shader ../../samba/mesa/src/gallium/drivers/radeonsi/si_shaderlib_tgsi.c:219
    #7 0x7ff722043ed9 in si_compute_do_clear_or_copy ../../samba/mesa/src/gallium/drivers/radeonsi/si_compute_blit.c:156
    #8 0x7ff7220448d3 in si_clear_buffer ../../samba/mesa/src/gallium/drivers/radeonsi/si_compute_blit.c:247
    #9 0x7ff7220350e8 in vi_dcc_clear_level ../../samba/mesa/src/gallium/drivers/radeonsi/si_clear.c:274

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>