libwebsockets: fix recursive dependency

libwebsockets: fix recursive dependency

While running `make menuconfig`, it was discovered then there is a
recursive dependency like this:
tmp/.config-package.in:59138:error: recursive dependency detected!
tmp/.config-package.in:59138:	symbol PACKAGE_libwebsockets-openssl is selected by PACKAGE_libwebsockets-mbedtls
tmp/.config-package.in:59122:	symbol PACKAGE_libwebsockets-mbedtls depends on PACKAGE_libwebsockets-openssl

It is not possible with the recently added conflicts that two packages
(OpenSSL and full variant, which uses OpenSSL as well), which are almost the same
provides the same named package libwebsockets as their conflict - Mbed
TLS.

Fixes: 676c5c72b5eeb583da2603e399fac085fa442c59 ("libwebsockets: OpenSSL
and mbedTLS variants should conflict")

Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>