PCI/AER: Clean up version indentation in ABI docs

The 'KernelVersion' lines use a single space as separator instead of a tab
so the values are not aligned with the other AER attribute fields.

Link: https://lore.kernel.org/r/20240202131635.11405-3-johan+linaro@kernel.org


Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>