iwlwifi: pcie: extend device reset delay

Newer hardware generations will take longer to be accessible again
after reset, so we need to wait longer before continuing any flow
that did a reset.

Rather than make the wait time configurable, simply extend it for
all.

Since all of these code paths can sleep, use usleep_range() rather
than mdelay().

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>