arm/addrenv_utils: Don't touch L1 mappings in addrenv_destroy()

This is unnecessary, the address environment is getting wiped anyway,
there is no need to remove the L1 references because they will get
wiped when the page directory is changed

arch/arm/src/armv7-a/arm_addrenv_utils.c

@@ -171,10 +171,6 @@ void arm_addrenv_destroy_region(uintptr_t **list, unsigned int listlen,
 
   for (i = 0; i < listlen; vaddr += SECTION_SIZE, i++)
     {
-      /* Unhook the L2 page table from the L1 page table */
-
-      mmu_l1_clrentry(vaddr);
-
       /* Has this page table been allocated? */
 
       paddr = (uintptr_t)list[i];