fsi: sbefifo: Fix sparse warnings

fsi-sbefifo.c:547:58: warning: incorrect type in argument 2 (different base types)
fsi-sbefifo.c:547:58:    expected restricted __be32 [usertype] *word
fsi-sbefifo.c:547:58:    got unsigned int *<noident>
fsi-sbefifo.c:635:16: warning: incorrect type in assignment (different base types)
fsi-sbefifo.c:635:16:    expected unsigned int [unsigned] <noident>
fsi-sbefifo.c:635:16:    got restricted __be32 [usertype] <noident>
fsi-sbefifo.c:636:16: warning: incorrect type in assignment (different base types)
fsi-sbefifo.c:636:16:    expected unsigned int [unsigned] <noident>
fsi-sbefifo.c:636:16:    got restricted __be32 [usertype] <noident>

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>