tests: drivers: spi: Remove redundant logging configurations
tests: drivers: spi: Remove redundant logging configurations

This commit removes the redundant `LOG` and `LOG_IMMEDIATE` selections
in `prj.conf`, since the `TEST_LOGGING_DEFAULTS`, which is enabled by
default for all tests, selects `LOG` and `LOG_MINIMAL`.

This effectively allows the test to run with the default test logging
policy, set by the testing subsystem.

Signed-off-by: Stephanos Ioannidis <dc76e9f0c0006e8f919e0c515c66dbba3982f785@stephanos.io>

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