bnxt_en: Restructure bnxt_flash_package_from_fw_obj() to execute in a loop.

On NICs with a smaller NVRAM, FW installation may fail after multiple
updates due to fragmentation.  The driver can retry when FW returns
a special error code.  To faciliate the retry, we restructure the
logic that performs the flashing in a loop.  The actual retry logic
will be added in the next patch.

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>