openpower sdk: Drop openpower-dbus-yaml dep

Now that the org.open_power D-BUS yaml moved into
phosphor-dbus-interfaces, don't need this anymore.

(From meta-openpower rev: 57d0db2abf2b433e72d7500593f367ccf47878e6)

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I99077e9e491a3600e21a98fa3bc03764bccf0d2e
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>