staging: remove i2o subsystem: some leftovers

[Valentin Rothberg]

Hi Greg,

your commit 4a72a7af462d ("staging: remove i2o subsystem") is in
today's linux-next tree (i.e., next-20150514) and it removes the
menuconfig I2O, but leaves the following line untouched:

drivers/Makefile:101:obj-$(CONFIG_I2O)          += message/

Can this line and the folder be removed or should it depend on another option?

I detected this issue with scripts/checkkconfigsymbols.py by diffing
yesterday's and today's linux-next tree.

Kind regards,
 Valentin