dgn_bottom() fix

Use the level passed in instead of the hero's location when checking
the dungeon branch.

It probably doesn't make any difference, but use the argument that's
already being provided.

src/trap.c

@@ -389,7 +389,7 @@ dng_bottom(d_level *lev)
         /* deepest reached < qlocate implies current < qlocate */
         if (dunlev_reached(lev) < qlocate_depth)
             bottom = qlocate_depth; /* early cut-off */
-    } else if (Inhell) {
+    } else if (In_hell(lev)) {
         /* if the invocation hasn't been performed yet, the vibrating square
            level is effectively the bottom of Gehennom; the sanctum level is
            out of reach until after the invocation */