wolfssl: bump to v4.7.0-stable

Biggest fix for this version is CVE-2021-3336, which has already been
applied here.  There are a couple of low severity security bug fixes as
well.

Three patches are no longer needed, and were removed; the one remaining
was refreshed.

This tool shows no ABI changes:
https://abi-laboratory.pro/index.php?view=objects_report&l=wolfssl&v1=4.6.0&v2=4.7.0



Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>