ics932s401: fix broken handling of errors when word reading fails

In commit b05ae01f, someone tried to make the driver handle i2c read
errors by simply zeroing out the register contents, but for some reason
left unaltered the code that sets the cached register value the function
call return value.

The original patch was authored by a member of the Underhanded
Mangle-happy Nerds, I'm not terribly surprised.  I don't have the
hardware anymore so I can't test this, but it seems like a pretty
obvious API usage fix to me...

Fixes: b05ae01f

 ("misc/ics932s401: Add a missing check to i2c_smbus_read_word_data")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20210428222534.GJ3122264@magnolia
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>