Tidy AP_Notify LED defines

[peterbarker]

Filtered output shows no binary output changes apart from these:

------------------------  -----  ----------  ------  -----  -----  -----  ----
Board                     blimp  bootloader  copter  heli   plane  rover  sub
PixSurveyA2               -192   *           -192    -192   -184   -192   -192
SITL_arm_linux_gnueabihf  0                  0       0      0      0      0
SITL_x86_64_linux_gnu     0                  0       0      0      0      0
obal                      -560               -4624   -4592  -560   -560   -592
------------------------  -----  ----------  ------  -----  -----  -----  ----

PixSurveyA2 was undeffing the pins for the board leds that it was inheriting, but wasn't undefining the feature, so it was suffering overhead when it didn't need to.

obal is only losing the relevant symbols. The large chunks on some targets seems to be down to an alignment change.