i2c: axxia: fixup return type of wait_for_completion_timeout

return type of wait_for_completion_timeout is unsigned long not int. The
return variable is renamed to reflect its use and the type adjusted to
unsigned long.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>