powerpc/powernv/pci: Fix m64 checks for SR-IOV and window alignment

Commit 5958d19a checks for prefetchable m64 BARs by comparing the
addresses instead of using resource flags.  This broke SR-IOV as the m64
check in pnv_pci_ioda_fixup_iov_resources() fails.

The condition in pnv_pci_window_alignment() also changed to checking
only IORESOURCE_MEM_64 instead of both IORESOURCE_MEM_64 and
IORESOURCE_PREFETCH.

Revert these cases to the previous behaviour, adding a new helper function
to do so.  This is named pnv_pci_is_m64_flags() to make it clear this
function is only looking at resource flags and should not be relied on for
non-SRIOV resources.

Fixes: 5958d19a ("Fix incorrect PE reservation attempt on some 64-bit BARs")
Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Russell Currey <ruscur@russell.cc>
Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>