i2c: octeon: remove unused signal handling

'commit 2637e5fd ("i2c: octeon: Fix i2c fail problem when a process is
terminated by a signal")' removed the wait_event_interruptible_timeout to
prevent half/mixed i2c messages from being sent/recievd but forgot to
drop the signal handling case in the return handling. This just removes
this dead code. While at it the return variable is adjusted to the type
expected.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>