icnss: Fix return value for register_driver

With change commit 0da8e4a2 ("icnss: Wait uninterruptible for
unregister driver"), return value changed from -ERESTARTSYS to -EINTR to
provide right return value to user space but as part of the change,
missed to update register driver case. Returning error even when driver
register is failed causes the module loader to remove the module because
of failure even though register driver as such is success.

CRs-fixed: 1078316
Change-Id: Ib3d13360def3ab47f121c66057c96977f5264043
Signed-off-by: Prashanth Bhatta <bhattap@codeaurora.org>