PCI: pciehp: Leave power indicator on when enabling already-enabled slot

PCI: pciehp: Leave power indicator on when enabling already-enabled slot

If an error occurs when enabling a slot, pciehp_power_thread() turns off
the power indicator.  But if the only error is that the slot was already
enabled, we should leave the power indicator on.

Return success if called to enable an already-enabled slot.
This is in the same spirit of the special handling for EEXISTS when
pciehp_configure_device() determines the slot devices already exist.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>