Fix REF_PRINT_COUNT argument in ecx_key_free

Fix REF_PRINT_COUNT argument in ecx_key_free

Currently, when configuring OpenSSL using -DREF_PRINT the following
compilation error is generated:

In file included from include/crypto/ecx.h:21,
                 from crypto/ec/ecx_key.c:11:
crypto/ec/ecx_key.c: In function 'ecx_key_free':
crypto/ec/ecx_key.c:65:32: error: 'r' undeclared
(first use in this function)
   65 |     REF_PRINT_COUNT("ECX_KEY", r);
      |                                ^
include/internal/refcount.h:169:40: note: in definition of macro
'REF_PRINT_COUNT'
  169 |         fprintf(stderr, "%p:%4d:%s\n", b, b->references, a)
      |                                        ^
crypto/ec/ecx_key.c:65:32: note: each undeclared identifier is reported
only once for each function it appears in
   65 |     REF_PRINT_COUNT("ECX_KEY", r);
      |                                ^
include/internal/refcount.h:169:40: note: in definition of macro
'REF_PRINT_COUNT'
  169 |         fprintf(stderr, "%p:%4d:%s\n", b, b->references, a)
      |                                        ^
make[1]: *** [Makefile:14929: crypto/ec/libcrypto-lib-ecx_key.o] Error 1

This commit updates the argument passed in to be the ECX_KEY* key.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/13298)