i2c-tools: don't include linux/i2c-dev.h

i2c-tools: don't include linux/i2c-dev.h

Installing headers from upstream i2c-tools makes it impossible to
build the busybox version due to redefined symbols. This is caused by
the fact that linux/i2c-dev.h from i2c-tools overwrites the one from
linux uapi and defines symbols already defined by linux' linux/i2c.h.

Drop this include and simply re-implement the relevant defines from
linux/i2c-dev.h in miscutils/i2c-tools.c.

Tested by building on systems with and without i2c-tools headers.

Signed-off-by: Bartosz Golaszewski <bartekgola@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>