disk: Fixed capacity message

With capacities getting bigger, we can see see messages with negative
numbers like "Capacity: 1907729.0 MB = 1863.0 GB (-387938128 x 512)".
Here the printed LBA is -387938128 when it should have been 3907029168.
To fix this, use the right format when displaying the unsigned integers.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reported-by: Yan Liu <yan-liu@ti.com>