lib: rsa: fix compilation error without openssl

The symbol TOOLS_IMAGE_PRE_LOAD doesn't depend on TOOLS_LIBCRYPTO.
If we choose to build tools without openssl, rsa_verify_openssl()
will attempt to call the unavailable openssl library functions.

Fixes: 942c8c8e6697 ("rsa: Add rsa_verify_openssl() to use openssl for host builds")
Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
diff --git a/lib/rsa/rsa-verify.c b/lib/rsa/rsa-verify.c
index 4a0418a..b65fbe4 100644
--- a/lib/rsa/rsa-verify.c
+++ b/lib/rsa/rsa-verify.c
@@ -570,7 +570,7 @@
 	uint8_t hash[info->crypto->key_len];
 	int ret;
 
-#ifdef USE_HOSTCC
+#if defined(USE_HOSTCC) && CONFIG_IS_ENABLED(LIBCRYPTO)
 	if (!info->fdt_blob)
 		return rsa_verify_openssl(info, region, region_count, sig, sig_len);
 #endif