i965: always enable EXT_float_blend

From the table in isl_format.c, it appears that all generations
support blending on 32-bit float surfaces.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/mesa/drivers/dri/i965/intel_extensions.c

@@ -97,6 +97,7 @@ intelInitExtensions(struct gl_context *ctx)
    ctx->Extensions.EXT_blend_func_separate = true;
    ctx->Extensions.EXT_blend_minmax = true;
    ctx->Extensions.EXT_draw_buffers2 = true;
+   ctx->Extensions.EXT_float_blend = true;
    ctx->Extensions.EXT_framebuffer_sRGB = true;
    ctx->Extensions.EXT_gpu_program_parameters = true;
    ctx->Extensions.EXT_packed_float = true;