In case something other than a block device is supplied, podman proceeds
to apply settings for a block device with the same minor:major.
For example, "--blkio-weight-device /dev/zero:123" (alas, this is taken
literally from podman-update(1) EXAMPLES section) sets blkio weight
for /dev/ram5. Instead, it should error out since /dev/zero is not a
block device.
Add an appropriate check.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>