drivers: llcc: Remove error message in llcc_slice_getd()

Don’t dump error logs incase of LLCC DT is properties
are not defined. These are non-fatal which are not
required in kernel logs when LLCC is not enabled.

Change-Id: I842dff07c7d5c958998535392dca57ed1f92cbdc
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>