Having test_pages_isolated failure message as a warning confuses users
into thinking that it is more serious than it really is.  In reality, if
called via CMA, allocation will be retried so a single
test_pages_isolated failure does not prevent allocation from succeeding.

Demote the warning message to an info message and reformat it such that
the text "failed" does not appear and instead a less worrying "PFNS
busy" is used.

This message is trivially reproducible on a 10GB x86 machine on 3.16.y
kernels configured with CONFIG_DMA_CMA.
Signed-off-by: NMichal Nazarewicz <mina86@mina86.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>