Documentation: ipcc: Rename compatible to not be SoC specific

Since the IPCC driver has no SoC specific dependency on Kona,
remove the 'kona' substring from its compatible.

Change-Id: If86ebcab398210c16104116331cf4733af433abe
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>