wimax/i2400m: if a device reboot happens during probe, handle it

When a device reboot happens when we are under probe, with init_mutex
taken, make sure we can recover. Have dev_reset_handle set boot mode
and i2400m_msg_to_dev() will see it and fail gracefully instead of
timing out.

Found and diagnosed by Cindy H. Kao.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
diff --git a/drivers/net/wimax/i2400m/fw.c b/drivers/net/wimax/i2400m/fw.c
index 26924f1..01c926e 100644
--- a/drivers/net/wimax/i2400m/fw.c
+++ b/drivers/net/wimax/i2400m/fw.c
@@ -985,6 +985,7 @@
 	d_fnstart(5, dev, "(i2400m %p bcf %p size %zu)\n",
 		  i2400m, bcf, bcf_size);
 	i2400m->boot_mode = 1;
+	wmb();		/* Make sure other readers see it */
 hw_reboot:
 	if (count-- == 0) {
 		ret = -ERESTARTSYS;
@@ -1033,6 +1034,7 @@
 	d_printf(2, dev, "fw %s successfully uploaded\n",
 		 i2400m->fw_name);
 	i2400m->boot_mode = 0;
+	wmb();		/* Make sure i2400m_msg_to_dev() sees boot_mode */
 error_dnload_finalize:
 error_dnload_bcf:
 error_dnload_init: