iwlwifi: pcie: Fix CSR_RESET operation access type

The access to the CSR_RESET reg should be done as a complete
DWORD and not by setting a bit. This is the right way to reset
the device.

Signed-off-by: Eran Harary <eran.harary@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>