btrfs: don't print the crc32c implementation at module load time

Btrfs can use various different checksumming algorithms, and prints
the one used for a given file system at mount time.  Don't bother
printing the crc32c implementation at module load time, the information
is available in /sys/fs/btrfs/FSID/checksum.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>