media: pci: ivtv: Add missing check after DMA map

media: pci: ivtv: Add missing check after DMA map

commit 1069a4fe637d0e3e4c163e3f8df9be306cc299b4 upstream.

The DMA map functions can fail and should be tested for errors.
If the mapping fails, free blanking_ptr and set it to 0.  As 0 is a
valid DMA address, use blanking_ptr to test if the DMA address
is set.

Fixes: 1a0adaf37c30 ("V4L/DVB (5345): ivtv driver for Conexant cx23416/cx23415 MPEG encoder/decoder")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>