Closing a wrapped key with the new SE driver interface while
MBEDTLS_PSA_CRYPTO_SE_C is also enabled leads to the key material not
being freed, even though an old SE driver is not in use, leading to a
memory leak. This is because a wrapped key is also considered external.
This commit extends the check for skipping by checking whether an
old-style SE driver is registered with the provided slot, in addition to
checking whether the key is external.
Signed-off-by: Fredrik Strupe <fredrik.strupe@silabs.com>