PM / suspend: Fix missing KERN_CONT for suspend message

Commit 4bcc595c (printk: reinstate KERN_CONT for printing
continuation lines) exposed a missing KERN_CONT from one of the
messages shown on entering suspend. With v4.9-rc1, the 'done.' shown
after syncing the filesystems no longer appears as a continuation but
a new message with its own timestamp.

[    9.259566] PM: Syncing filesystems ... [    9.264119] done.

Fix this by adding the KERN_CONT log level for the 'done.' part of the
message seen after syncing filesystems. While we are at it, convert
these suspend printks to pr_info and pr_cont, respectively.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>