<linux/of.h>: add stub for of_get_next_parent() to fix qcom build error

<linux/of.h>: add stub for of_get_next_parent() to fix qcom build error

Fix a (COMPILE_TEST) build error when CONFIG_OF is not set/enabled
by adding a stub for of_get_next_parent().

../drivers/soc/qcom/qcom-geni-se.c:819:11: error: implicit declaration of function 'of_get_next_parent'; did you mean 'of_get_parent'? [-Werror=implicit-function-declaration]
../drivers/soc/qcom/qcom-geni-se.c:819:9: warning: assignment makes pointer from integer without a cast [-Wint-conversion]

Fixes: 048eb908a1f2 ("soc: qcom-geni-se: Add interconnect support to fix earlycon crash")
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: devicetree@vger.kernel.org
Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: linux-arm-msm@vger.kernel.org
Link: https://lore.kernel.org/r/ce0d7561-ff93-d267-b57a-6505014c728c@infradead.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>