drm/rockchip: dw_hdmi: Fix reading EDID when using a forced mode

EDID cannot be read on RK3328 until after read_hpd has been called and
correct io voltage has been configured based on connection status.

When a forced mode is used, e.g. video=1920x1080@60e, the connector
detect ops, that in turn normally calls the read_hpd, never gets called.

This result in reading EDID to fail in connector get_modes ops.

Call dw_hdmi_rk3328_read_hpd at end of dw_hdmi_rk3328_setup_hpd to
correct io voltage and allow reading EDID after setup_hpd.

Fixes: 1c53ba8f ("drm/rockchip: dw_hdmi: add dw-hdmi support for the rk3328")
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240615170417.3134517-5-jonas@kwiboo.se