boards: disco_l475_iot1: Enable I2C_1 in default config
boards: disco_l475_iot1: Enable I2C_1 in default config

I2C_1 is enabled in board's DT file but we need to enable
it also in boards default config.

I2C_0 doesn't exist in STM32L475 SOC.

Signed-off-by: Yannis Damigos <bda985a2727ac24c41652a294292988d6fc7dc73@gmail.com>

finikorg/zephyr,punitvara/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,kraj/zephyr,kraj/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,galak/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,mbolivar/zephyr,aceofall/zephyr-iotos,zephyriot/zephyr,kraj/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,aceofall/zephyr-iotos,zephyriot/zephyr,explora26/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,mbolivar/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,nashif/zephyr,punitvara/zephyr,nashif/zephyr,zephyriot/zephyr,nashif/zephyr,explora26/zephyr,nashif/zephyr,Vudentz/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,punitvara/zephyr,galak/zephyr,aceofall/zephyr-iotos,ldts/zephyr,mbolivar/zephyr,finikorg/zephyr,zephyriot/zephyr,Vudentz/zephyr,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,ldts/zephyr,galak/zephyr,zephyriot/zephyr,Vudentz/zephyr,nashif/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,kraj/zephyr,mbolivar/zephyr,kraj/zephyr,explora26/zephyr,ldts/zephyr,punitvara/zephyr,aceofall/zephyr-iotos,mbolivar/zephyr,punitvara/zephyr