isdn: hfcpci: check the return value of dma_set_mask() in setup_hw()

The function dma_set_mask() in setup_hw() can fail, so its return value
should be checked.

Fixes: 1700fe1a

 ("Add mISDN HFC PCI driver")
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>