Not doing the MTD test on FMUv3 in rc.apm

[gmorph]

The if test is specifically checking for FMU v2 - this needs to be fixed.

[OXINARF]

I think this wasn't already the case when this was opened (last version before this was opened doesn't have any board check:

ardupilot/mk/PX4/ROMFS/init.d/rc.APM

Lines 374 to 390 in ab96e98

	if mtd start /fs/mtd
	then
	echo "started mtd driver OK"
	else
	echo "failed to start mtd driver"
	echo "failed to start mtd driver" >> $logfile
	sh /etc/init.d/rc.error
	fi
	if mtd readtest /fs/mtd
	then
	echo "mtd readtest OK"
	else
	echo "failed to read mtd"
	echo "failed to read mtd" >> $logfile
	sh /etc/init.d/rc.error
	fi

), but it certainly doesn't happen today - this check has been moved to code instead of init file: https://github.com/ArduPilot/ardupilot/blob/master/libraries/AP_HAL_PX4/Storage.cpp#L200-L209.