btrfs: always update fstrim_range on failure in FITRIM ioctl

btrfs: always update fstrim_range on failure in FITRIM ioctl

Even in case of failure we could've discarded some data and userspace
should be made aware of it, so copy fstrim_range to userspace
regardless.

Also make sure to update the trimmed bytes amount even if
btrfs_trim_free_extents fails.

CC: [email protected] # 5.15+
Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Luca Stefani <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>