media: media/pci: prevent memory leak in bttv_probe

In bttv_probe if some functions such as pci_enable_device,
pci_set_dma_mask and request_mem_region fails the allocated
 memory for btv should be released.

Signed-off-by: Xiaolong Huang <butterflyhuangxx@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>