Revert "Fixed race condition where the control bit to start PVT interpolation mode could occur before enough pvt segments were loaded into a servo's buffer"

This reverts commit 2c9d6e54bd867ad3ff66e39bbc73aaafea978ff9.
fixed bug in pvt mode status.

the bit flag I was using to determine if pvt mode was active is
actually a flag that gets reused for other things in other modes,
so if you don't check what mode you're in and read the flag, you're
very sad about the results. this should fix the race condition brandon
attempted to fix earlier.
clear pvt buffers when exiting pvt mode.

also, only print pvt errors in pvt mode. this is relevant because
clearing the pvt buffers causes "buffer empty" errors, but we don't
care because we're leaving pvt mode anyways.