presence: Un-hardcode input device path

Allow a device path to be configured.

Change-Id: I2eabd71747b124eae96738d1332f58b96ece6dc9
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/presence/templates/gpio.mako.hpp b/presence/templates/gpio.mako.hpp
index fb1f46f..d2a25d8 100644
--- a/presence/templates/gpio.mako.hpp
+++ b/presence/templates/gpio.mako.hpp
@@ -1,2 +1,2 @@
 std::make_unique<PolicyAccess<Gpio, ConfigPolicy>>(
-${indent(1)}${g.policy}, "${g.physpath}"s, ${g.key})\
+${indent(1)}${g.policy}, "${g.physpath}"s, "${g.devpath}"s, ${g.key})\