fiemap: Eliminate num_extents

fiemap: Eliminate num_extents

Fiemap has this rather convoluted logic to calculate the number of extents to
query. This introduces needless complexity with no real benefit. Remove
num_extents and instead hardcode the number of extents we query for in a single
go to 32. No functional changes

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>