PCI/MSI: Handle msi_populate_sysfs() errors correctly

PCI/MSI: Handle msi_populate_sysfs() errors correctly

Previously, when msi_populate_sysfs() failed, we saved the error return
value as dev->msi_irq_groups, which leads to a page fault when
free_msi_irqs() calls msi_destroy_sysfs().

To prevent this, leave dev->msi_irq_groups alone when msi_populate_sysfs()
fails.

Found by the Hulk Robot when injecting a memory allocation fault in
msi_populate_sysfs():

  BUG: unable to handle page fault for address: fffffffffffffff4
  ...
  Call Trace:
   msi_destroy_sysfs+0x30/0xa0
   free_msi_irqs+0x11d/0x1b0

Fixes: 2f170814bdd2 ("genirq/msi: Move MSI sysfs handling from PCI to MSI core")
Link: https://lore.kernel.org/r/20211012071556.939137-1-wanghai38@huawei.com
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Barry Song <song.bao.hua@hisilicon.com>