drm/msm/dsi/phy: Toggle back buffer resync after preparing PLL

drm/msm/dsi/phy: Toggle back buffer resync after preparing PLL

According to Hardware Programming Guide for DSI PHY, the retime buffer
resync should be done after PLL clock users (byte_clk and intf_byte_clk)
are enabled.  Downstream also does it as part of configuring the PLL.

Driver was only turning off the resync FIFO buffer, but never bringing it
on again.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/657823/
Link: https://lore.kernel.org/r/20250610-b4-sm8750-display-v6-6-ee633e3ddbff@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>