gfs2: Avoid unnecessary transactions in evict_linked_inode

gfs2: Avoid unnecessary transactions in evict_linked_inode

In evict_linked_inode(), the truncate_inode_pages() calls are carried
out inside a transaction.  This code was added to what was then function
gfs2_delete_inode() in commit 16615be18cadf ("[GFS2] Clean up journaled
data writing").

These transactions are only used for creating revokes for the jdata
buffers in the journal, so don't create such transactions when we know
that the address space doesn't contain any jdata buffers for this inode
and truncate the metadata address space outside of the transaction.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>