ROMFS: If UAVCAN is enabled, reduce log buffer size

This is necessary to make the space for UAVCAN in memory and doing it this way avoids negatively impacting users who do not use UAVCAN.

ROMFS/px4fmu_common/init.d/rcS

@@ -196,6 +196,7 @@ then
 	set MAV_TYPE none
 	set FAILSAFE none
 	set USE_IO yes
+	set LOGGER_BUF 16
 
 	#
 	# Set USE_IO flag
@@ -738,6 +739,7 @@ then
 	then
 		if uavcan start
 		then
+			set LOGGER_BUF 7
 			uavcan start fw
 		else
 			tone_alarm ${TUNE_ERR}
@@ -875,9 +877,10 @@ then
 			then
 				set LOGGER_ARGS "-m mavlink"
 			fi
-			if logger start -b 16 -t ${LOGGER_ARGS}
+			if logger start -b ${LOGGER_BUF} -t ${LOGGER_ARGS}
 			then
 			fi
+			unset LOGGER_BUF
 			unset LOGGER_ARGS
 		fi
 	fi