ARM: dts: msm: Add dummy support for mdmfermium clocks

Mark dummy provider for gcc,debug clocks on mdmfermium to
unblock clients depending on clocks. Also Remove clock_rpm labels
as clock_gcc is the provider for both gcc and rpm clocks.

Change-Id: Ib75b4361d2de8fb65c55b9ba346989ffa6491d8c
Signed-off-by: Jaydeep Sen <jsen@codeaurora.org>