net: mscc: make sparse happy

This patch fixes a sparse warning about using an incorrect type in
argument 2 of ocelot_write_rix(), as an u32 was expected but a __be32
was given. The conversion to u32 is forced, which is safe as the value
will be written as-is in the hardware without any modification.

Fixes: 08d02364 ("net: mscc: fix the injection header")
Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>