xen/arm: mm: Remove special case for CPU0 in dump_hyp_walk()

xen/arm: mm: Remove special case for CPU0 in dump_hyp_walk()

There is no need to have a special case for CPU0 when converting the
page-table virtual address into a physical address. The helper
virt_to_maddr() is able to translate any address as long as the root
page-tables is mapped in the virtual address. This is the case for all
the CPUs at the moment.

So use the same BUG_ON() regardless the CPU.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
[julien: Rework the commit message]
Signed-off-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>