This helps in debugging. We can look at the dmesg to find out
different kernel mapping details.

On 4K config this shows

 kernel vmalloc start   = 0xc000100000000000
 kernel IO start        = 0xc000200000000000
 kernel vmemmap start   = 0xc000300000000000

On 64K config:

 kernel vmalloc start   = 0xc008000000000000
 kernel IO start        = 0xc00a000000000000
 kernel vmemmap start   = 0xc00c000000000000
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>