staging/bcm: fix most build warnings

This removes all warnings I get on a 64 bit build except
for those that look unfixable, where we convert a pointer
to a 32 bit integer and change its byte order!

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>