[decompiler] fix (gpr->fpr when an integer arg is converted to float (#482)

* fix gpr fpr bug

* remove unused variable

test/decompiler/reference/engine/ps2/pad_REF.gc

@@ -180,8 +180,7 @@
 (defun
   analog-input
   ((in int) (offset float) (center-val float) (max-val float) (out-range float))
-  (let* ((in (gpr->fpr in))
-         (offset-in (- (the float in) offset))
+  (let* ((offset-in (- (the float in) offset))
          (magnitude (- (fabs offset-in) center-val))
          (max-magnitude (- max-val center-val))
          )
@@ -367,7 +366,3 @@
 ;; failed to figure out what this is:
 (let ((v0-4 0))
   )
-
-
-
-