drm/radeon: add PX quirk for Asus K73TK

drm/radeon: add PX quirk for Asus K73TK

BugLink: http://bugs.launchpad.net/bugs/1773233
commit b1550359d1eb392ee54f7cf47cffcfe0a602f6a7 upstream.

With this the dGPU turns on correctly.

Signed-off-by: Nico Sneck <nicosneck@hotmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>