ice: move and rename ice_check_for_pending_update

The ice_devlink_flash_update function performs a few checks and then
calls ice_flash_pldm_image. One of these checks is to call
ice_check_for_pending_update. This function checks if the device has
a pending update, and cancels it if so. This is necessary to allow
a new flash update to proceed.

We want to refactor the ice code to eliminate ice_devlink_flash_update,
moving its checks into ice_flash_pldm_image.

To do this, ice_check_for_pending_update will become static, and only
called by ice_flash_pldm_image. To make this change easier to review,
first just move the function up within the ice_fw_update.c file.

While at it, note that the function has a misleading name. Its primary
action is to cancel a pending update. Using the verb "check" does not
imply this. Rename it to ice_cancel_pending_update.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>