sparc: remove driver-core BUS_ID_SIZE

The name size limit is gone from the driver-core, the BUS_ID_SIZE
value will be removed.

Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>