staging: greybus: Replace function gb_i2c_device_setup()

Remove function gb_i2c_device_setup as all it does is call
gb_i2c_functionality_operation.
Rename gb_i2c_functionality_operation to gb_i2c_device_setup to maintain
compatibility with call sites.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190705131131.27354-1-nishkadg.linux@gmail.com


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