bpf: add missing break in for the TCP_BPF_SNDCWND_CLAMP case

bpf: add missing break in for the TCP_BPF_SNDCWND_CLAMP case

There appears to be a missing break in the TCP_BPF_SNDCWND_CLAMP case.
Currently the non-error path where val is greater than zero falls through
to the default case that sets the error return to -EINVAL. Add in
the missing break.

Detected by CoverityScan, CID#1449376 ("Missing break in switch")

Fixes: 13bf96411ad2 ("bpf: Adds support for setting sndcwnd clamp")
Signed-off-by: Colin Ian King <[email protected]>
Acked-by: Daniel Borkmann <[email protected]>
Acked-by: Lawrence Brakmo <[email protected]>
Signed-off-by: David S. Miller <[email protected]>