UserspaceEmulator: Simplify the definition of the FPU register stack

Long doubles are always at least 80 bits wide in memory and it suffices
if we can address these 80 bits, to mark the long double as NAN at the
end of an MMX instruction, so the additional magic using conditional
types is unnecessary.

Userland/DevTools/UserspaceEmulator/SoftFPU.h

@@ -289,12 +289,7 @@ private:
         long double fp;
         struct {
             MMX mmx;
-            Conditional<sizeof(long double) == 16,
-                u64,
-                Conditional<sizeof(long double) == 12,
-                    u32,
-                    u16>>
-                __high;
+            u16 __high;
         };
     } m_storage[8];