mlxsw: spectrum: mr: Fix various endianness issues

Fix various endianness issues in comparisons and assignments. The fix is
entirely cosmetic as all the values fixed are endianness-agnostic.

Cleans up sparse warnings:
spectrum_mr.c:156:49: warning: restricted __be32 degrades to integer
spectrum_mr.c:206:26: warning: restricted __be32 degrades to integer
spectrum_mr.c:212:31: warning: incorrect type in assignment (different
  base types)
spectrum_mr.c:212:31:    expected restricted __be32 [usertype] addr4
spectrum_mr.c:212:31:    got unsigned int
spectrum_mr.c:214:32: warning: incorrect type in assignment (different
  base types)
spectrum_mr.c:214:32:    expected restricted __be32 [usertype] addr4
spectrum_mr.c:214:32:    got unsigned int
spectrum_mr.c:461:16: warning: restricted __be32 degrades to integer
spectrum_mr.c:461:49: warning: restricted __be32 degrades to integer

Fixes: c011ec1b

 ("mlxsw: spectrum: Add the multicast routing offloading logic")
Signed-off-by: Yotam Gigi <yotamg@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>