firmware: use dev_printk when possible

Convert printks to use dev_printk().

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>