package/uftp: fix compilation with openssl
Build fails with -lssl but succeeds with -lcrypto, also thats how it is
linked by default in 'makefile'.
Fixes:
http://autobuild.buildroot.net/results/01a455ddcbc16cd2111352d22bf6603842df4ab2
Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>