i2c: designware: fixup return handling of wait_for_completion_timeout

return type of wait_for_completion_timeout is unsigned long not int, rather
than introducing a new variable the wait_for_completion_timeout is moved
into the if condition as the return value is only used to detect timeout.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Reviewed-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>