Return an error code if of_property_count_u32_elems() fails.  Don't
return success.

Fixes: e656cd0b ("soc: qcom: rmtfs: Optionally map RMTFS to more VMs")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/76b21a14-70ff-4ca9-927d-587543c6699c@kili.mountain