net: aquantia: replace AQ_HW_WAIT_FOR with readx_poll_timeout_atomic

David noticed the original define was hiding 'err' variable
reference. Thats confusing and counterintuitive.

Andrew noted the whole macro could be replaced with standard readx_poll
kernel macro. This makes code more readable.

Signed-off-by: Nikita Danilov <nikita.danilov@aquantia.com>
Signed-off-by: Igor Russkikh <igor.russkikh@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>