radv: fix VK_KHR_shader_float_controls dependency on GFX6-7

radv: fix VK_KHR_shader_float_controls dependency on GFX6-7

From the Vulkan spec 1.1.126 :
   "VK_SHADER_FLOAT_CONTROLS_INDEPENDENCE_32_BIT_ONLY_KHR specifies
    that shader float controls for 32-bit floating point can be set
    independently; other bit widths must be set identically to each
    other."

Forgot to update this when I enabled that extension recently.

Fixes dEQP-VK.spirv_assembly.instruction.compute.float_controls.independence_settings.independence_setting

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>