crypto: streebog - use correct endianness type

streebog_uint512::qword needs to be __le64, not u64.  This fixes a large
number of sparse warnings:

    crypto/streebog_generic.c:25:9: warning: incorrect type in initializer (different base types)
    crypto/streebog_generic.c:25:9:    expected unsigned long long
    crypto/streebog_generic.c:25:9:    got restricted __le64 [usertype]
    [omitted many similar warnings]

No actual change in behavior.

Cc: Vitaly Chikunov <vt@altlinux.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>