ARM: dts: msm: Fix RPM devices on APQ8084

Remove a duplicate rpm-smd device and remove the
rpm-standalone property, which is no longer necessary due
to the target having a real RPM image.

Change-Id: I594eff9dac6b3cad4b6f54f81cd129c7842389c8
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>