dt-bindings: clock: gcc-msm8998: Add HMSS_GPLL0_CLK_SRC definition

Add new clock definition to gcc-msm8998 dt-bindings

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Link: https://lore.kernel.org/r/20210114221059.483390-4-angelogioacchino.delregno@somainline.org


Signed-off-by: Stephen Boyd <sboyd@kernel.org>