PCI: pci-bridge-emul: Add PCIe Root Capabilities Register

PCI: pci-bridge-emul: Add PCIe Root Capabilities Register

commit e902bb7c24a7099d0eb0eb4cba06f2d91e9299f3 upstream.

The 16-bit Root Capabilities register is at offset 0x1e in the PCIe
Capability. Rename current 'rsvd' struct member to 'rootcap'.

Link: https://lore.kernel.org/r/20210722144041.12661-4-pali@kernel.org
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>