nfp: debug dump - decrease endian conversions

Convert the requested dump level parameter to big-endian at the start of
nfp_net_dump_calculate_size() and nfp_net_dump_populate_buffer(), then
compare and assign it directly where needed in the traversal and prolog
code. This decreases the total number of conversions used.

Signed-off-by: Carl Heymann <carl.heymann@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>