ehea: Fix memory hotplug oops

ehea: Fix memory hotplug oops

The ehea driver oopses during memory hotplug if the ports are not
up. A simple testcase:

# ifconfig ethX down
# echo offline > /sys/devices/system/memory/memory32/state

Oops: Kernel access of bad area, sig: 11 [#1]
last sysfs file: /sys/devices/system/memory/memory32/state
REGS: c000000709393110 TRAP: 0300   Not tainted  (2.6.39-rc2-01385-g7ef73bc-dirty)
DAR: 0000000000000000, DSISR: 40000000
...
NIP [c000000000067c98] .__wake_up_common+0x48/0xf0
LR [c00000000006d034] .__wake_up+0x54/0x90
Call Trace:
[c00000000006d034] .__wake_up+0x54/0x90
[d000000006bb6270] .ehea_rereg_mrs+0x140/0x730 [ehea]
[d000000006bb69c4] .ehea_mem_notifier+0x164/0x170 [ehea]
[c0000000006fc8a8] .notifier_call_chain+0x78/0xf0
[c0000000000b3d70] .__blocking_notifier_call_chain+0x70/0xb0
[c000000000458d78] .memory_notify+0x28/0x40
[c0000000001871d8] .remove_memory+0x208/0x6d0
[c000000000458264] .memory_section_action+0x94/0x140
[c0000000004583ec] .memory_block_change_state+0xdc/0x1d0
[c0000000004585cc] .store_mem_state+0xec/0x160
[c00000000044768c] .sysdev_store+0x3c/0x50
[c00000000020b48c] .sysfs_write_file+0xec/0x1f0
[c00000000018f86c] .vfs_write+0xec/0x1e0
[c00000000018fa88] .SyS_write+0x58/0xd0

To fix this, initialise the waitqueues during port probe instead
of port open.

Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: stable@kernel.org
Acked-by: Breno Leitao <leitao@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>