hwrng: omap - Fix RNG wait loop timeout

Existing RNG data read timeout is 200us but it doesn't cover EIP76 RNG
data rate which takes approx. 700us to produce 16 bytes of output data
as per testing results. So configure the timeout as 1000us to also take
account of lack of udelay()'s reliability.

Fixes: 38321242 ("hwrng: omap - Add device variant for SafeXcel IP-76 found in Armada 8K")
Cc: <stable@vger.kernel.org>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>