s3/rpc_client: change type of offset to uint64_t

s3/rpc_client: change type of offset to uint64_t

Offset can be a 32 or 64 bit address depending on the indexing addressing
mode negotiated by the client
With a 32 bit param we can only specify a 32 bit base address. This change
alone doesn't affect anything as it is the client itself that choses and
passes the base address offset and wspsearch is the only current user of
this code.
In this case even with 64bit addressing negotiated the address passed
represents only the lower 32-bits part of the address.
However, for coverage purposes it would be better for the client to use an
address that covers the full 64bit range of the address (when 64 bit
addressing is negotiated).
This change will alow the wspsearch client in a future commit to pass a
base address value with both the hi and low 32 bits values set to make up
the full 64 bit address.

Signed-off-by: Noel Power <noel.power@suse.com>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>