icE1usb fw: Add GPSDO VCXO trimming loop

Rather basic and not super well tested, use with caution

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: I5f9ce6621492be967d6a44d31f270e107f3ef686
diff --git a/firmware/ice40-riscv/icE1usb/Makefile b/firmware/ice40-riscv/icE1usb/Makefile
index a6e9138..25c65d1 100644
--- a/firmware/ice40-riscv/icE1usb/Makefile
+++ b/firmware/ice40-riscv/icE1usb/Makefile
@@ -49,6 +49,7 @@
 	config.h \
 	e1.h \
 	gps.h \
+	gpsdo.h \
 	ice1usb_proto.h \
 	misc.h \
 	usb_desc_ids.h \
@@ -62,6 +63,7 @@
 	e1.c \
 	fw_app.c \
 	gps.c \
+	gpsdo.c \
 	misc.c \
 	usb_desc_app.c \
 	usb_dev.c \