AP_RCProtocol: fixed support for 22ms multi-frame DSM

libraries/AP_RCProtocol/AP_RCProtocol_DSM.cpp

@@ -139,6 +139,8 @@ void AP_RCProtocol_DSM::dsm_guess_format(bool reset, const uint8_t dsm_frame[16]
         0xff,	/* 8 channels (DX8) */
         0x1ff,	/* 9 channels (DX9, etc.) */
         0x3ff,	/* 10 channels (DX10) */
+        0x7ff,	/* 11 channels DX8 22ms */
+        0xfff,	/* 12 channels DX8 22ms */
         0x1fff,	/* 13 channels (DX10t) */
         0x3fff	/* 18 channels (DX10) */
     };