[pallet-broker] Use saturating math in input validation (#4151)
Changes:
- Saturate in the input validation of he drop history function or
pallet-broker.
---------
Signed-off-by: 
Oliver Tale-Yazdi <[email protected]>
Changes:
- Saturate in the input validation of he drop history function or
pallet-broker.
---------
Signed-off-by: Oliver Tale-Yazdi <[email protected]>