net: dsa: qca8k: reduce mgmt ethernet timeout

The current mgmt ethernet timeout is set to 100ms. This value is too
big and would slow down any mdio command in case the mgmt ethernet
packet have some problems on the receiving part.
Reduce it to just 5ms to handle case when some operation are done on the
master port that would cause the mgmt ethernet to not work temporarily.

Fixes: 5950c7c0 ("net: dsa: qca8k: add support for mgmt read/write in Ethernet packet")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Link: https://lore.kernel.org/r/20220621151633.11741-1-ansuelsmth@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>