In su3000_read_mac_address, if i2c_transfer fails to execute two
messages, array mac address will not be initialized. Without handling
such error, later in function dvb_usb_adapter_dvb_init, proposed_mac
is accessed before initialization.

Fix this error by returning a negative value if message execution fails.

Link: https://lore.kernel.org/linux-media/20230328124416.560889-1-harperchen1110@gmail.comSigned-off-by: Wei Chen <harperchen1110@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>