arm64: Print physical address of page table base in show_pte()

When dumping the page table in response to an unexpected kernel page
fault, we print the virtual (hashed) address of the page table base, but
display physical addresses for everything else.

Make the page table dumping code in show_pte() consistent, by printing
the page table base pointer as a physical address.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>