i965: Turn brw_get_line_width_float() into brw_get_line_width().

i965: Turn brw_get_line_width_float() into brw_get_line_width().

Drop the old brw_get_line_width() helper which return the unsigned
fixed-point encoding of the line width - it's been dead since the
conversion to GENXML (which does the encoding for us).

Then rename brw_get_line_width_float() to the shorter name.

Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>