funclatency: remove unnecessary include

[brendangregg]

# ./funclatency.py 'go:fmt.Println'
In file included from /virtual/main.c:3:
In file included from /lib/modules/4.9.0-rc5-virtual/build/include/linux/blkdev.h:9:
In file included from /lib/modules/4.9.0-rc5-virtual/build/include/linux/genhd.h:64:
In file included from /lib/modules/4.9.0-rc5-virtual/build/include/linux/device.h:24:
In file included from /lib/modules/4.9.0-rc5-virtual/build/include/linux/pinctrl/devinfo.h:21:
In file included from /lib/modules/4.9.0-rc5-virtual/build/include/linux/pinctrl/consumer.h:17:
In file included from /lib/modules/4.9.0-rc5-virtual/build/include/linux/seq_file.h:10:
/lib/modules/4.9.0-rc5-virtual/build/include/linux/fs.h:2693:9: warning: comparison of unsigned enum expression < 0 is always false [-Wtautological-compare]
        if (id < 0 || id >= READING_MAX_ID)
            ~~ ^ ~
1 warning generated.

That unnecessary include was also throwing this unnecessary warning.

PS. That warning should be fixed in Linux 4.11/4.12 (it made it into mm recently).

[drzaeus77]

[buildbot, test this please]

Just a side note, one of the two issues with the buildbots seems to have gotten better. That is, I no longer see boot-up failures on the fedora slaves. The failure in this PR is due to a race condition in tearing down the one-time-use slaves. I'll try playing with some timeouts and hopefully this failure will stop showing up too.