scsi: sd: Print write through due to no caching mode page as warning

For SD cardreaders it is extremely common not to have a cache.
Consequently, the following messages do not point to a real error one could
try to fix but rather describe how the disk works:

  sd 0:0:0:0: [sda] No Caching mode page found
  sd 0:0:0:0: [sda] Assuming drive cache: write through

Print these messages as warnings instead of errors.

Link: https://lore.kernel.org/r/20211013075050.3870354-1-martin.kepplinger@puri.sm


Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>