[ECONET]: remove econet_packet_type on unload

[ECONET]: remove econet_packet_type on unload

Steps to reproduce:

	modprobe econet
	rmmod econet
	modprobe econet

Unable to handle kernel paging request at ffffffff8870a098 RIP:
 [<ffffffff8040bfb8>] dev_add_pack+0x48/0x90
PGD 203067 PUD 207063 PMD 7817f067 PTE 0
Oops: 0002 [1] PREEMPT SMP
CPU 1
Modules linked in: econet [maaaany]
Pid: 10671, comm: modprobe Not tainted 2.6.23-rc3-bloat #6
RIP: 0010:[<ffffffff8040bfb8>]  [<ffffffff8040bfb8>] dev_add_pack+0x48/0x90
RSP: 0000:ffff810076293df8  EFLAGS: 00010202
RAX: ffffffff88659090 RBX: ffffffff88659060 RCX: ffffffff8870a090
RDX: 0000000000000080 RSI: ffffffff805ec660 RDI: ffff810078ce4680
RBP: ffff810076293e08 R08: 0000000000000002 R09: 0000000000000000
R10: ffffffff8040bf88 R11: 0000000000000001 R12: ffff810076293e18
R13: 000000000000001b R14: ffff810076dd06b0 R15: ffffffff886590c0
FS:  00002b96a525dae0(0000) GS:ffff81007e0e2138(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: ffffffff8870a098 CR3: 000000007bb67000 CR4: 00000000000026e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process modprobe (pid: 10671, threadinfo ffff810076292000, task ffff810078ce4680)
Stack:  ffff810076dd06b0 0000000000000000 ffff810076293e38 ffffffff8865b180
 0000000000800000 0000000000000000 ffffffff886590c0 ffff810076dd01c8
 ffff810076293f78 ffffffff8026723c ffff810076293e48 ffffffff886590d8
Call Trace:
 [<ffffffff8865b180>] :econet:econet_proto_init+0x180/0x1da
 [<ffffffff8026723c>] sys_init_module+0x15c/0x19e0
 [<ffffffff8020c13e>] system_call+0x7e/0x83

Code: 48 89 41 08 48 89 82 e0 c5 5e 80 48 c7 c7 a0 08 5d 80 e8 f1
RIP  [<ffffffff8040bfb8>] dev_add_pack+0x48/0x90
 RSP <ffff810076293df8>
CR2: ffffffff8870a098

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>