If the attempt to map a page for DMA fails (eg, because we're out of
mapping space) then we must not hold on to the page we allocated for
DMA - doing so will result in a memory leak.
Cc: <stable@kernel.org> Reported-by: Bryan Phillippe <bp@darkforest.org> Tested-by: Bryan Phillippe <bp@darkforest.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>