drm/amd/display: Fix vblank refcount in vrr transition

manage_dm_interrupts disable/enable vblank using drm_crtc_vblank_off/on
which causes drm_crtc_vblank_get in vrr_transition to fail, and later
when drm_crtc_vblank_put is called the refcount on vblank will be messed
up. Therefore move the call to after manage_dm_interrupts.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1247
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1380

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Yunxiang Li <Yunxiang.Li@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org