demo: Fix makefile target
The makefile target was incorrect and wouldn't build the rsa_encrypt demo.
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20503)
(cherry picked from commit 67bfdfa17bc4ca8e2b819316299bb82748394c45)