i2c: __must_check fixes, i2c-dev

i2c: __must_check fixes, i2c-dev

i2c: __must_check fixes (i2c-dev)

Check for error on sysfs file creation.
Check for error on device creation.
Delete sysfs file on device destruction.

I couldn't test this one beyond compilation, as it applies on top of
another patch in Greg's tree [1] which breaks all my systems when I
apply it (my udev isn't recent enough.) Anyone with bleeding edge udev
is welcome to test and report.

[1] http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/i2c/i2c-dev-device.patch

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>