Allow the shell to disable charging.

Bug: 204184680
Test: manual and through instrumentation
Change-Id: I1fe9b35d51140eccba9c05c956875c512de447b1
diff --git a/private/shell.te b/private/shell.te
index 709e0b7..63746f6 100644
--- a/private/shell.te
+++ b/private/shell.te
@@ -94,6 +94,9 @@
 # userspace reboot
 set_prop(shell, userspace_reboot_test_prop)
 
+# Allow shell to set this property to disable charging.
+set_prop(shell, power_debug_prop)
+
 # Allow shell to set this property used for rollback tests
 set_prop(shell, rollback_test_prop)