drm/amd/display: hpd rx irq not working with eDP interface

[Why]
This is the fix for the defect of commit ab144f0b
("drm/amd/display: Allow individual control of eDP hotplug support").

[How]
To revise the default eDP hotplug setting and use the enum to git rid
of the magic number for different options.

Fixes: ab144f0b ("drm/amd/display: Allow individual control of eDP hotplug support")
Cc: stable@vger.kernel.org
Cc: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Robin Chen <robin.chen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>