RCOutput_iofirmware.cpp carried a second copy of the decode table, used by
the reversed-channel decoder on STM32F1. That copy is live: PB8 and PA1 are
declared BIDIR on iomcu-f103-dshot, so those channels kept the old
one-in-sixteen false accept rate while the main path was fixed.
Hoist the table, the quintet check and the checksum into one helper so the
two cannot drift again. Removing the duplicate saves 172 bytes on the F103,
which has 8k of flash left.
Andy Piper
2e0ee77b4d