extras/boards.txt: Disable the V1 plugin API by default

As this is a new port, there is little sense in supporting the legacy API.
Disable it for some nice space savings!

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

extras/boards.txt

@@ -20,4 +20,4 @@ ergodox.build.usb_manufacturer="ErgoDox EZ"
 ergodox.build.board=AVR_ERGODOX
 ergodox.build.core=arduino:arduino
 ergodox.build.variant=ergodox
-ergodox.build.extra_flags={build.usb_flags} '-DKALEIDOSCOPE_HARDWARE_H="Kaleidoscope-Hardware-ErgoDox.h"'
+ergodox.build.extra_flags={build.usb_flags} '-DKALEIDOSCOPE_HARDWARE_H="Kaleidoscope-Hardware-ErgoDox.h"' '-DKALEIDOSCOPE_ENABLE_V1_PLUGIN_API=0'