The snd_hdac_chip_readl return can never be less than zeros,
so no point in checking for the return value

This fixes following static checker warnings in
snd_hdac_ext_bus_parse_capabilities

       sound/hda/ext/hdac_ext_controller.c:47
 snd_hdac_ext_bus_parse_capabilities()
       warn: unsigned 'offset' is never less than zero.

       sound/hda/ext/hdac_ext_controller.c:54
 snd_hdac_ext_bus_parse_capabilities()
       warn: unsigned 'cur_cap' is never less than zero.
Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>