ltq-vdsl-app: Fix counter overflow resulting in negative values

ltq-vdsl-app: Fix counter overflow resulting in negative values

The re-transmit counters can overflow the 32 bit representation resulting
in negative values being displayed. Background being that the numbers are
treated at some point as signed INT rather than unsigned INT.
Change the counters from 32 bit to 64 bit, should provide sufficient room
to avoid any overflow. Not the nicest solution but it works

Fixes: #10077
Signed-off-by: Roland Barenbrug <roland@treslong.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
(cherry picked from commit 456b9029d764e69f390ee26bca24883b12eb83c2)