crypto/evp/ctrl_params_translate.c: fix a typo in the error message

crypto/evp/ctrl_params_translate.c: fix a typo in the error message

The ERR_raise_data() call on failure to find ctx->p2 in str_value_map
erroneously refers to ctx->p1 instead;  fix that but supplying the
correct field and casting it to the supposed const char * type.

Fixes: 9a1c4e41e8d3 "EVP: Implement data-driven translation between known ctrl and OSSL_PARAMs"
Resolves: https://scan5.scan.coverity.com/#/project-view/65248/10222?selectedIssue=1665427
References: https://github.com/openssl/project/issues/1432
Signed-off-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28649)