staging: comedi: pcl812: remove acl8216_ai_insn_read()

staging: comedi: pcl812: remove acl8216_ai_insn_read()

This (*insn_read) function was used to read 16-bit analog input data
from the boardACL8216 boardtypes. The 12/16-bit differences are now
handled by the pcl812_ai_eoc() and pcl812_ai_get_sample() helpers.

Remove this function and use pcl812_ai_insn_read() for all boardtypes.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>