i2c: reduce parent checking to a NOOP in non-I2C_MUX case
i2c: reduce parent checking to a NOOP in non-I2C_MUX case

In 0826374 - i2c: Multiplexed I2C bus core support
core i2c code increased in size and complexity even when I2C_MUX
wasn't selected.

Turning this check into a constant NULL in the n case lets the
client functions in be simplified too, not needing to include
never-called calls to the mux-specific helpers.

Signed-off-by: Phil Carmody <670ff7e763af3eb1bb08dc61c69d43f6d97dd671@partner.samsung.com>
Signed-off-by: Wolfram Sang <fd4ce474653598159cad06f3c83387a05cd53a44@the-dreams.de>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs