PCI/sysfs: Use correct variable for the legacy_mem sysfs object

PCI/sysfs: Use correct variable for the legacy_mem sysfs object

Two legacy PCI sysfs objects "legacy_io" and "legacy_mem" were updated
to use an unified address space in the commit d298c1ef1e62 ("PCI: Revoke
mappings like devmem").  This allows for revocations to be managed from
a single place when drivers want to take over and mmap() a /dev/mem
range.

Following the update, both of the sysfs objects should leverage the
iomem_get_mapping() function to get an appropriate address range, but
only the "legacy_io" has been correctly updated - the second attribute
seems to be using a wrong variable to pass the iomem_get_mapping()
function to.

Thus, correct the variable name used so that the "legacy_mem" sysfs
object would also correctly call the iomem_get_mapping() function.

Fixes: d298c1ef1e62 ("PCI: Revoke mappings like devmem")
Link: https://lore.kernel.org/r/20210812132144.791268-1-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>