staging: greybus: i2c.c: remove commented out function

Remove function gb_i2c_smbus_xfer() which is unused.

Signed-off-by: Lourdes Pedrajas <lu@pplo.net>
Link: https://lore.kernel.org/r/20200309170643.4947-1-lu@pplo.net


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>