PCI: Add PCI_EXP_SLTCTL_ASPL_DISABLE macro

Add macro defining Auto Slot Power Limit Disable bit in Slot Control
Register.

Link: https://lore.kernel.org/r/20220412094946.27069-2-pali@kernel.org


Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>