iomap: Remove pgoff from tracepoints

The 'pgoff' displayed by the tracepoints wasn't a pgoff at all; it
was a byte offset from the start of the file.  We already emit that in
the form of the 'offset', so we can just remove pgoff.  That means we
can remove 'page' as an argument to the tracepoint, and rename this
type of tracepoint from being a page class to being a range class.

Fixes: 0b1b213f ("xfs: event tracing support")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>