sencha: remove submodule update depth when sync'ing cheriot-rtos

This fixes "fatal: transport 'file' not allowed" CI complaints.

Bypass-Presubmit-Reason: previously tested

Change-Id: I306a1051fad93c91e1bd7902d35cee703418c1c7

platforms/sencha/cheriot.mk

diff --git a/platforms/sencha/cheriot.mk b/platforms/sencha/cheriot.mk
index 0e5e4d4..790f01a 100644
--- a/platforms/sencha/cheriot.mk
+++ b/platforms/sencha/cheriot.mk
@@ -104,7 +104,7 @@
 cheriot_check:
 	echo Updating $(CHERIOT_SRC_DIR) submodules...; \
 	git -C $(CHERIOT_SRC_DIR) submodule sync && \
-		git -C $(CHERIOT_SRC_DIR) submodule update --init --jobs=8 --depth=10; \
+		git -C $(CHERIOT_SRC_DIR) submodule update --init --jobs=8;
 
 
 # Build CHERIoT firmware image.