clk: qcom: mmcc-msm8996: Migrate gfx3d clock to clk_rcg2_gfx3d

clk: qcom: mmcc-msm8996: Migrate gfx3d clock to clk_rcg2_gfx3d

In the previous commit ("clk: qcom: rcg2: Stop hardcoding gfx3d pingpong
parent numbers") the gfx3d ping-pong ops (clk_gfx3d_ops) were
generalized in order to be able to reuse the same ops for more than just
one clock for one SoC: follow the change here in the MSM8996 MMCC.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Link: https://lore.kernel.org/r/20210113183817.447866-7-angelogioacchino.delregno@somainline.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>