Fix var name.

Signed-off-by: Pan Li <[email protected]>

lib/float/inf.sail

@@ -35,10 +35,10 @@ $include <float/common.sail>
 val      float_is_inf : fp_bits -> bool
 function float_is_inf (op) = {
   let struct {_, exp, mantissa} = float_decompose(op);
-  let is_nan = exp == sail_ones(length(exp))
+  let is_inf = exp == sail_ones(length(exp))
                & mantissa == sail_zeros(length(mantissa));
 
-  is_nan
+  is_inf
 }
 
 $endif