PCI/MSI: Set pci_dev:: Msi_enabled late

The comment claiming that pci_dev::msi_enabled has to be set across setup
is a leftover from ancient code versions. Nothing in the setup code
requires the flag to be set anymore.

Set it in the success path and remove the extra goto label.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/all/20250319105506.383222333@linutronix.de