net: ipv4: remove redundant initialization in inet_rtm_deladdr

The initialization for 'err' with '-EINVAL' is redundant and
can be removed, as it is updated soon.

Changes since v1:
- Remove redundant empty line

Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Link: https://lore.kernel.org/r/20201108010541.12432-1-dong.menglong@zte.com.cn


Signed-off-by: Jakub Kicinski <kuba@kernel.org>