powerpc/cell: Bitops work on unsigned longs

So change the flags member of struct spu from u64 to unsigned long.
This change will also prevent some warnings when we change u64 to unsigned
long long.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>