Fix coral usb permissions

Previously you had to manually change permissions for the coral
between every reboot, this change fixes that.

Signed-off-by: Filip Kujawa <filip.j.kujawa@gmail.com>
Change-Id: I30291282c816d981765138daaf11037e64e73c6c
diff --git a/frc971/rockpi/build_rootfs.sh b/frc971/rockpi/build_rootfs.sh
index d19a260..d61fb48 100755
--- a/frc971/rockpi/build_rootfs.sh
+++ b/frc971/rockpi/build_rootfs.sh
@@ -229,6 +229,7 @@
 copyfile root.root 644 etc/udev/rules.d/99-usb-mount.rules
 copyfile root.root 644 etc/udev/rules.d/99-adis16505.rules
 copyfile root.root 644 etc/udev/rules.d/99-mali.rules
+copyfile root.root 644 etc/udev/rules.d/99-coral-perms.rules
 copyfile root.root 644 etc/chrony/chrony.conf
 
 target "apt-get update"