[IPV4]: Unify and cleanup calls to devinet_sysctl_register

[IPV4]: Unify and cleanup calls to devinet_sysctl_register

Currently this call is used to register sysctls for devices
and for the "default" confs. The "all" sysctls are registered
separately.

Besides, the inet_device is passed to this function, but it is
not needed there at all - just the device name and ifindex are
required.

Thanks to Herbert, who noticed, that this call doesn't even
require the devconf pointer (the last argument) - all we need
we can take from the in_device itself.

The fix is to make a __devinet_sysctl_register(), which registers
sysctls for all "devices" we need, including "default" and "all" :)

The original devinet_sysctl_register() works with struct net_device,
not the inet_device, and calls the introduced function, passing
the device name and ifindex (to be used as procname and ctl_name)
into it.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>