sysfs: sysfs_update_group stub for CONFIG_SYSFS=n

scsi_transport_spi uses sysfs_update_group() when CONFIG_SYSFS=n,
so provide a stub for it.

next-20080423/drivers/scsi/scsi_transport_spi.c:1467: error: implicit declaration of function 'sysfs_update_group'
make[3]: *** [drivers/scsi/scsi_transport_spi.o] Error 1

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>