[media] zoran: don't build it on alpha

This driver uses virt_to_bus() with is deprecated on Alpha:
	drivers/media/pci/zoran/zoran_device.c: In function 'zr36057_set_vfe':
	drivers/media/pci/zoran/zoran_device.c:451:3: warning: 'virt_to_bus' is deprecated (declared at /devel/v4l/ktest-build/arch/alpha/include/asm/io.h:114) [-Wdeprecated-declarations]
	drivers/media/pci/zoran/zoran_device.c:453:3: warning: 'virt_to_bus' is deprecated (declared at /devel/v4l/ktest-build/arch/alpha/include/asm/io.h:114) [-Wdeprecated-declarations]
	drivers/media/pci/zoran/zoran_device.c: In function 'zr36057_set_jpg':
	drivers/media/pci/zoran/zoran_device.c:796:2: warning: 'virt_to_bus' is deprecated (declared at /devel/v4l/ktest-build/arch/alpha/include/asm/io.h:114) [-Wdeprecated-declarations]
	drivers/media/pci/zoran/zoran_driver.c: In function 'v4l_fbuffer_alloc':
	drivers/media/pci/zoran/zoran_driver.c:241:3: warning: 'virt_to_bus' is deprecated (declared at /devel/v4l/ktest-build/arch/alpha/include/asm/io.h:114) [-Wdeprecated-declarations]
	drivers/media/pci/zoran/zoran_driver.c:245:3: warning: 'virt_to_bus' is deprecated (declared at /devel/v4l/ktest-build/arch/alpha/include/asm/io.h:114) [-Wdeprecated-declarations]
	drivers/media/pci/zoran/zoran_driver.c: In function 'jpg_fbuffer_alloc':
	drivers/media/pci/zoran/zoran_driver.c:334:3: warning: 'virt_to_bus' is deprecated (declared at /devel/v4l/ktest-build/arch/alpha/include/asm/io.h:114) [-Wdeprecated-declarations]
	drivers/media/pci/zoran/zoran_driver.c:347:5: warning: 'virt_to_bus' is deprecated (declared at /devel/v4l/ktest-build/arch/alpha/include/asm/io.h:114) [-Wdeprecated-declarations]
	drivers/media/pci/zoran/zoran_driver.c:366:6: warning: 'virt_to_bus' is deprecated (declared at /devel/v4l/ktest-build/arch/alpha/include/asm/io.h:114) [-Wdeprecated-declarations]
As we're not even sure if it works on Alpha, better to just disable its compilation there.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>