iwlwifi: increase PNVM load timeout

The FW has a watchdog of 200ms in the PNVM load flow, so the driver
should have a slightly higher timeout.  Change the timeout from 100ms
to 250ms.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Fixes: 70d3ca86 ("iwlwifi: mvm: ring the doorbell and wait for PNVM load completion")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210612142637.ba22aec1e2be.I36bfadc28c480f4fc57266c075a79e8ea4a6934f@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>