[nrf temphack] prj.conf: don't use CONFIG_LOG_MODE_MINIMAL yet

MCUboot was updated to newer version which uses refactored
LOG Kconfig keyword not available in sdk-zephyr yet.

Revert this commit on the next upmerge.

Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>

boot/zephyr/prj.conf

@@ -31,7 +31,7 @@ CONFIG_FPROTECT=y
 # CONFIG_I2C is not set
 
 CONFIG_LOG=y
-CONFIG_LOG_MODE_MINIMAL=y # former CONFIG_MODE_MINIMAL
+CONFIG_LOG_MINIMAL=y
 ### Ensure Zephyr logging changes don't use more resources
 CONFIG_LOG_DEFAULT_LEVEL=0
 ### Decrease footprint by ~4 KB in comparison to CBPRINTF_COMPLETE=y