hwrng: hisi - remove HiSilicon TRNG driver

Driver of HiSilicon true random number generator(TRNG)
is removed from 'drivers/char/hw_random'.

Both 'Kunpeng 920' and 'Kunpeng 930' chips have TRNG,
however, PRNG is only supported by 'Kunpeng 930'.
So, this driver is moved to 'drivers/crypto/hisilicon/trng/'
in the next to enable the two's TRNG better.

Signed-off-by: Weili Qian <qianweili@huawei.com>
Reviewed-by: Zaibo Xu <xuzaibo@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>