btrfs: remove redundant stop_loop variable in scrub_stripe()

btrfs: remove redundant stop_loop variable in scrub_stripe()

The variable stop_loop was originally introduced in commit 625f1c8dc66d7
("Btrfs: improve the loop of scrub_stripe"). It was initialized to 0 in
commit 3b080b2564287 ("Btrfs: scrub raid56 stripes in the right way").
However, in a later commit 18d30ab961497 ("btrfs: scrub: use
scrub_simple_mirror() to handle RAID56 data stripe scrub"), the code
that modified stop_loop was removed, making the variable redundant.

Currently, stop_loop is only initialized with 0 and is never used or
modified within the scrub_stripe() function. As a result, this patch
removes the stop_loop variable to clean up the code and eliminate
unnecessary redundancy.

This change has no impact on functionality, as stop_loop was never
utilized in any meaningful way in the final version of the code.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Riyan Dhiman <riyandhiman14@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>