common: skip tests using LVM when the device is no known

common: skip tests using LVM when the device is no known

LVM has a lot of elaborate code to make the users life painful.  This
includes claiming the device type is unknown if it doesn't match it's
elaborately crafted internal list instead of just letting the user use
it.  Skip tests using LVM if this is the case to avoid arcane failures
due to missing lvm devices when using null_blk.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Zorro Lang <zlang@kernel.org>