sdlog2: Do not abort startup without microSD

ROMFS/px4fmu_common/init.d/rc.logging

@@ -7,10 +7,12 @@ if [ -d /fs/microsd ]
 then
 	if ver hwcmp PX4FMU_V1
 	then
-		echo "Start sdlog2 at 50Hz"
-		sdlog2 start -r 40 -a -b 3 -t
+		if sdlog2 start -r 40 -a -b 3 -t
+		then
+		fi
 	else
-		echo "Start sdlog2 at 200Hz"
-		sdlog2 start -r 200 -a -b 22 -t
+		if sdlog2 start -r 200 -a -b 22 -t
+		then
+		fi
 	fi
 fi

ROMFS/px4fmu_common/init.d/rcS

@@ -42,6 +42,8 @@ else
 			tone_alarm MNBG
 			set LOG_FILE /dev/null
 		fi
+	else
+		set LOG_FILE /dev/null
 	fi
 fi