xtensa: adjust boot parameters address when INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX is selected

The virtual address of boot parameters chain is passed to the kernel via
a2 register. Adjust it in case it is remapped during MMUv3 -> MMUv2
mapping change, i.e. when it is in the first 128M.

Also fix interpretation of initrd and FDT addresses passed in the boot
parameters: these are physical addresses.

Cc: stable@vger.kernel.org
Reported-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
xtensa: check TLB sanity on return to userspace

- check that user TLB mappings correspond to the current page table;
- check that TLB mapping VPN is in the kernel/user address range
  in accordance with its ASID.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>