net/i40e/base: sync nvmupdate command and adminq subtask
During NVMupdate, state machine gets into unrecoverable state because
i40e_clean_adminq_subtask can get scheduled after the admin queue
command but before other state variables are updated.
This patch adds locking around admin queue command and update of
state variables so that adminq_subtask will have accurate information
whenever it gets scheduled.