net: tcp: Remove redundant initialization of variable len

net: tcp: Remove redundant initialization of variable len

The variable len being initialized with a value that is never read, an
if statement is initializing it in both paths of the if statement.
The initialization is redundant and can be removed.

Cleans up clang scan build warning:
net/ipv4/tcp_ao.c:512:11: warning: Value stored to 'len' during its
initialization is never read [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Link: https://lore.kernel.org/r/20240216125443.2107244-1-colin.i.king@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>