arm64: defconfig: Enable I2C_GPIO

The GPIO-based bitbanging I2C driver is required to configure
CSI data, clock pins on CSI block in Allwinner A64 SoC.

Let build it as module.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>