With a clock interval of 400 nsec and a 64 bit transactions (32 bit
preamble & 16 bit control & 16 bit data), it is reasonable to assume
the mdio transaction will take 25.6 usec. Add a 30 usec delay before
the first poll to reduce the chance of a 1000-2000 usec sleep.
Reduce the timeout from 1000ms to 100ms as it is unlikely for the bus
to take this long.
Signed-off-by: Justin Chen <justin.chen@xxxxxxxxxxxx>