ext4: remove sbi argument from ext4_chksum()

Since ext4_chksum() no longer uses its sbi argument, remove it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Link: https://patch.msgid.link/20250513053809.699974-2-ebiggers@kernel.org


Signed-off-by: Theodore Ts'o <tytso@mit.edu>