i2c: isch: Add missed 'else'

In accordance with the existing comment and code analysis
it is quite likely that there is a missed 'else' when adapter
times out. Add it.

Fixes: 5bc12008 ("i2c: Add Intel SCH SMBus support")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: <stable@vger.kernel.org> # v2.6.27+
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>