RC/Joystick Cal: Fix stick detect and min detect

[DonLakeFlyer]

They should use _calValidMin/MaxValue to determine whether the stick has moved far enough away from center to consider it's position as a min/max value. Right now it just triggers on some minimal movement.

Related to #13915

[DonLakeFlyer]

@HTRamsey Says: Also FYI for bottom LS and bottom RS, you seem to have to go the other way from neutral a bit and then go to the target extreme to get it to register correctly.

Need to double check that.