bnxt_en: Clear DEFRAG flag in firmware message when retry flashing.

When the FW tells the driver to retry the INSTALL_UPDATE command after
it has cleared the NVM area, the driver is not clearing the previously
used ALLOWED_TO_DEFRAG flag. As a result the FW tries to defrag the NVM
area a second time in a loop and can fail the request.

Fixes: 1432c3f6

 ("bnxt_en: Retry installing FW package under NO_SPACE error condition.")
Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>