drm/bridge: ite-it6263: Move chip initialization code from probe to atomic_enable

drm/bridge: ite-it6263: Move chip initialization code from probe to atomic_enable

On the RZ/G3L SMARC EVK, suspend to RAM powers down the ITE IT6263 chip.
The display controller driver's system PM callbacks invoke
drm_mode_config_helper_{suspend,resume}, which in turn call the bridge's
atomic_{disable,enable} callbacks to handle suspend/resume for the bridge
without dedicated PM ops.

To support proper reinitialization after power loss, move reset_gpio into
the it6263 struct so it is accessible beyond probe time. Relocate
it6263_hw_reset(), it6263_lvds_set_i2c_addr(), it6263_lvds_config() and
it6263_hdmi_config() from probe to atomic_enable, ensuring the chip is
fully reset and reconfigured on every enable, including after a
suspend/resume cycle.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Liu Ying <victor.liu@nxp.com>
Link: https://patch.msgid.link/20260501061200.20129-1-biju.das.jz@bp.renesas.com
Signed-off-by: Liu Ying <victor.liu@nxp.com>