ext2: remove redundant assignment to pointer end

Pointer is assigned a value that is never read, the assignment is
redundant and can be removed.

Cleans up clang-scan warning:
fs/ext2/xattr.c:555:3: warning: Value stored to 'end' is never read [deadcode.DeadStores]
                end = (char *)header + sb->s_blocksize;

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230317143420.419005-1-colin.i.king@gmail.com>