drm/amd/display: Disable unneeded hpd interrupts during dm_init

[Why]

It seems HPD interrupts are enabled by default for all connectors, even
if the hpd source isn't valid. An eDP for example, does not have a valid
hpd source (but does have a valid hpdrx source; see construct_phy()).
Thus, eDPs should have their hpd interrupt disabled.

In the past, this wasn't really an issue. Although the driver gets
interrupted, then acks by writing to hw registers, there weren't any
subscribed handlers that did anything meaningful (see
register_hpd_handlers()).

But things changed with the introduction of IPS. s2idle requires that
the driver allows IPS for DMUB fw to put hw to sleep. Since register
access requires hw to be awake, the driver will block IPS entry to do
so. And no IPS means no hw sleep during s2idle.

This was the observation on DCN35 systems with an eDP. During suspend,
the eDP toggled its hpd pin as part of the panel power down sequence.
The driver was then interrupted, and acked by writing to registers,
blocking IPS entry.

[How]

Since DC marks eDP connections as having invalid hpd sources (see
construct_phy()), DM should disable them at the hw level. Do so in
amdgpu_dm_hpd_init() by disabling all hpd ints first, then selectively
enabling ones for connectors that have valid hpd sources.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>