gpio-presence: Add function to bind/unbind drivers

The cards that this app is doing presence detection for
may have devices with drivers that need to be bound and
unbound when the card is added and removed, respectively.

The drivers to do this to will be passed into the app
on startup (in a future commit).  Then when presence detect
changes the proper binds/unbinds will be done.

This commit adds the code in the Presence class to do so.

Change-Id: I32827e45b88ddb7586aba6b819cc591b49aa9c51
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
4 files changed