emul: spi: emul_bmi160: Rename 'spi' to 'bus'
emul: spi: emul_bmi160: Rename 'spi' to 'bus'

Update the language to refer to a bus instead of SPI. This will make it
more applicable with I2C support is added.

Signed-off-by: Simon Glass <c00b0378376498bd9cd974c388df8854c0131d27@chromium.org>

Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr