mlxsw: core: Increase timeout during firmware flash process

mlxsw: core: Increase timeout during firmware flash process

During the firmware flash process, some of the EMADs get timed out, which
causes the driver to send them again with a limit of 5 retries. There are
some situations in which 5 retries is not enough and the EMAD access fails.
If the failed EMAD was related to the flashing process, the driver fails
the flashing.

The reason for these timeouts during firmware flashing is cache misses in
the CPU running the firmware. In case the CPU needs to fetch instructions
from the flash when a firmware is flashed, it needs to wait for the
flashing to complete. Since flashing takes time, it is possible for pending
EMADs to timeout.

Fix by increasing EMADs' timeout while flashing firmware.

Fixes: ce6ef68f433f ("mlxsw: spectrum: Implement the ethtool flash_device callback")
Signed-off-by: Shalom Toledo <shalomt@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>