powerpc/drmem: Make lmb_size 64 bit

powerpc/drmem: Make lmb_size 64 bit

commit ec72024e35dddb88a81e40071c87ceb18b5ee835 upstream.

Similar to commit 89c140bbaeee ("pseries: Fix 64 bit logical memory block panic")
make sure different variables tracking lmb_size are updated to be 64 bit.

This was found by code audit.

Cc: stable@vger.kernel.org
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Acked-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201007114836.282468-2-aneesh.kumar@linux.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>