AP_OSD: use internal enumeration in place of mavlink enumeration

[peterbarker]

this will let us more-easily compile without the mavlink headers

Board                    AP_Periph  blimp  bootloader  copter  heli  iofirmware  plane  rover  sub
CubeOrange-periph-heavy  *                                                                     
Durandal                            *      *           0       0                 0      0      *
Hitec-Airspeed           *                                                                     
KakuteH7-bdshot                     *      *           0       0                 0      0      *
MatekF405                           *      *           0       0                 0      0      *
Pixhawk1-1M-bdshot                  *                  *       *                 *      *      *
f103-QiotekPeriph        *                                                                     
f303-Universal           *                                                                     
iomcu                                                                *                         
revo-mini                           *      *           0       0                 0      0      *
skyviper-v2450                                         *