Fix JVM signatures involving multi-dimensional array types

Apparently ASM's Type#getElementType returns the type of the array even if it's
multi-dimensional, so the loop was incorrect

compiler/testData/loadJava/compiledKotlin/annotations/MultiDimensionalArrayMethod.kt

@@ -0,0 +1,12 @@
+//ALLOW_AST_ACCESS
+package test
+
+annotation class Anno(val s: String)
+
+trait T {
+    Anno("foo")
+    fun foo(): Array<Array<Array<T>>>
+
+    Anno("bar")
+    val bar: Array<Array<BooleanArray>>
+}