net/rds: remove variable total_copied

Variable total_copied is just being incremented and it's never used
anywhere else. The variable and the increment are redundant so
remove it.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20221024135046.2159523-1-colin.i.king@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>