i965: Move fs_inst::has_side_effects()'s eot check to the parent class.

This eliminates a layer of wrapping, and makes a backend_instruction
sufficient.  The downside is that it exposes 'eot' to the vec4 backend,
which it doesn't need, but can basically happily ignore.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Tested-by: Pallavi G <pallavi.g@intel.com>

src/intel/compiler/brw_ir_fs.h

@@ -347,7 +347,6 @@ public:
    unsigned size_read(int arg) const;
    bool can_do_source_mods(const struct gen_device_info *devinfo);
    bool can_change_types() const;
-   bool has_side_effects() const;
    bool has_source_and_destination_hazard() const;
 
    /**
@@ -367,7 +366,6 @@ public:
 
    uint8_t sources; /**< Number of fs_reg sources. */
 
-   bool eot:1;
    bool pi_noperspective:1;   /**< Pixel interpolator noperspective flag */
 };