[PATCH] IR/imon: add auto-config for 0xffdc rf device

Add auto-config support for iMON 2.4G LT RF device, based on debug output from Giulio Amodeo in Red Hat bugzilla #572288. Also flips the switch on only setting up the rf associate sysfs attr only if we think we're looking at an RF device, vs. previously, setting up the attr for all 0xffdc devices,

[PATCH] IR/imon: add auto-config for 0xffdc rf device

Add auto-config support for iMON 2.4G LT RF device, based on debug output from Giulio Amodeo in Red Hat bugzilla #572288. Also flips the switch on only setting up the rf associate sysfs attr only if we think we're looking at an RF device, vs. previously, setting up the attr for all 0xffdc devices,