mailbox: mtk-cmdq: Refine GCE_GCTL_VALUE setting

Add cmdq_gctl_value_toggle() to configure GCE_CTRL_BY_SW and GCE_DDR_EN
together in the same GCE_GCTL_VALUE register.

For the SoCs whose GCE is located in MMINFRA and uses MMINFRA_AO power,
this allows it to be written without enabling the clocks. Otherwise, all
GCE registers should be written after the GCE clocks are enabled.
Move this function into cmdq_runtime_resume() and cmdq_runtime_suspend()
to ensure it is called when the GCE clock is enabled.

Fixes: 7abd037a ("mailbox: mtk-cmdq: add gce ddr enable support flow")
Signed-off-by: Jason-JH Lin <jason-jh.lin@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>