PCI: dwc: ep: Fix advertised resizable BAR size regression

PCI: dwc: ep: Fix advertised resizable BAR size regression

The advertised resizable BAR size was fixed in commit 72e34b8593e0 ("PCI:
dwc: endpoint: Fix advertised resizable BAR size").

Commit 867ab111b242 ("PCI: dwc: ep: Add a generic dw_pcie_ep_linkdown()
API to handle Link Down event") was included shortly after this, and
moved the code to another function. When the code was moved, this fix
was mistakenly lost.

According to the spec, it is illegal to not have a bit set in
PCI_REBAR_CAP, and 1 MB is the smallest size allowed.

So, set bit 4 in PCI_REBAR_CAP, so that we actually advertise support
for a 1 MB BAR size.

Fixes: 867ab111b242 ("PCI: dwc: ep: Add a generic dw_pcie_ep_linkdown() API to handle Link Down event")
Link: https://lore.kernel.org/r/20241116005950.2480427-2-cassel@kernel.org
Link: https://lore.kernel.org/r/20240606-pci-deinit-v1-3-4395534520dc@linaro.org
Link: https://lore.kernel.org/r/20240307111520.3303774-1-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Cc: stable@vger.kernel.org