Determine the various ARM64 kernel virtual address ranges using the
kernel's VA_BITS value.  It currently is hardwired in the kernel to
one of two values depending upon whether 4K or 64K pages are
configured.  However, there are plans to support 16K paqes, to make
VA_BITS a configurable value, and to make the number of page-table
levels configurable.  Towards that end, the crash utility has been
changed to determine the VA_BITS value based upon known kernel
virtual addresses, and to then calculate the relevant kernel virtual
address ranges on that value instead of hardwiring them based upon
the page size.
(anderson@redhat.com)