Disable doxygen in jenkins for embedded tests

There's no point in regenerating documentation with Doxygen in embedded
environment.

Change-Id: I6504db04445f5e9c1117379c8803e10df5634324
diff --git a/contrib/jenkins-arm.sh b/contrib/jenkins-arm.sh
index beb53da..e0c75fa 100755
--- a/contrib/jenkins-arm.sh
+++ b/contrib/jenkins-arm.sh
@@ -7,6 +7,7 @@
 	--prefix=/usr/local/arm-none-eabi \
 	--host=arm-none-eabi \
 	--enable-embedded \
+	--disable-doxygen \
 	--disable-shared \
 	CFLAGS="-Os -ffunction-sections -fdata-sections -nostartfiles -nodefaultlibs -Werror"