crypto/bio/bss_file.c: add missing cast in format arg in ERR_raise_data()

crypto/bio/bss_file.c: add missing cast in format arg in ERR_raise_data()

"%s" conversion specifier requires a "char *" argument, so ptr needs
to be cast to it there, as Coverity has noted.

Fixes: ff988500c2f39 "Replace FUNCerr with ERR_raise_data"
Resolves: https://scan5.scan.coverity.com/#/project-view/65248/10222?selectedIssue=1665423
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/28647)