net: sockets: Update msg_controllen in recvmsg properly

According to recvmsg man page, msg_controllen should be set to the sum
of the length of all control messages in the buffer.
This is missing from the current recvmsg implementation.
This commit aims to fix this by updating msg_controllen each time control
data are added to the buffer.
This commit also fixes cases where the msg_controllen is cleared
incorrectly.

Fixes #77303

Signed-off-by: Axel Le Bourhis <axel.lebourhis@nxp.com>
(cherry picked from commit 5d643f4b)