PCI: Disable MSI for ULi M1575 EHCI controller

With MSI, the ULi M1575 EHCI controller (10b9:5239) intermittently stops
executing its asynchronous schedule. Control transfers time out ("device
not accepting address", "device descriptor read/64"), the port is handed to
the companion OHCI controller, and the device ends up at full speed. On a
configured hub the stall shows up as hub descriptor and status read
failures. Only re-initializing the controller recovers it.

On a Sun Ultra 45, 65 of 800 controller initializations stalled with MSI
and none of 200 with INTx. Each initialization is an unbind and bind of
ehci-pci on the EHCI function, with MSI or INTx selected through its
msi_bus attribute; with this quirk, 0 of 100 cycles of the same loop
stalled. The stall reproduces on a kernel that already contains commit
0b60557230ad ("usb: ehci: Prevent missed ehci interrupts with
edge-triggered MSI").

The OHCI functions (10b9:5237) keep MSI. They showed no stall, and the hub
enumerated through them on MSI during the EHCI failures, so only the EHCI
function is quirked.

The illumos EHCI driver also disables MSI on this chip, in
ehci_register_intrs_and_init_mutex() in
usr/src/uts/common/io/usb/hcd/ehci/ehci_util.c.

Until USB HCDs started trying MSI first in v5.9, the controller always used
INTx. Disable MSI so it uses INTx again on this chipset.

Fixes: 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI devices")
Signed-off-by: Imre Kaloz <kaloz@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260930191100.6127-1-kaloz@kernel.org

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