Enable PXE boot on meson-gxbb.

Enable distro_bootcmd PXE functions on meson-gxbb systems.

Signed-off-by: Vagrant Cascadian <vagrant@debian.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/include/configs/meson-gxbb-common.h b/include/configs/meson-gxbb-common.h
index 12a4dfc..89e3807 100644
--- a/include/configs/meson-gxbb-common.h
+++ b/include/configs/meson-gxbb-common.h
@@ -40,6 +40,7 @@
 	func(MMC, mmc, 0) \
 	func(MMC, mmc, 1) \
 	func(MMC, mmc, 2) \
+	func(PXE, pxe, na) \
 	func(DHCP, dhcp, na)
 
 #include <config_distro_bootcmd.h>