This commit adds the possibility to check for expander errors when
reading the data. This is optional if glerr_check or interr_check
fields in configuration are not zero.
If not zero, read operation also reads ISO1I813T_GLERR and
ISO1I813T_INTERR register and returns error if there is some error.
The user can control which errors he wants to check with
glerr_check and interr_check masks.
Signed-off-by: Michal Lenc <michallenc@seznam.cz>