greybus: Fix unbalanced irq_enable() backtrace

Tip-of-tree is exhibiting a backtrace when loading-up the set of greybus
kernel modules due to calling arche_platform_wd_irq_en() directly after a
call to devm_request_threaded_irq().

At the point we call arch_platform_wd_irq_en() the relevant IRQ will
already be enabled. What we want to do in this situation is configure the
GPIO line as an input. This patch fixes the backtrace by supplanting
arche_platform_wd_irq_en() with
gpio_direction_input(arche_pdata->wake_detect_gpio) in
arche_platform_probe().

WARNING: at msm-ara-3.10/kernel/irq/manage.c:457 __enable_irq+0x74/0xc0()
Unbalanced enable for IRQ 687
Modules linked in: gb_arche(O+) gb_camera(O) gb_es2(O) gb_vibrator(O)
gb_raw(O) gb_power_supply(O) gb_loopback(O) gb_light(O) gb_hid(O)
greybus(O)
CPU: 0 PID: 415 Comm: insmod Tainted: G        W  O 3.10.78-g2a4dec8 #65
Call trace:
[<ffffffc000206adc>] dump_backtrace+0x0/0x248
[<ffffffc000206d34>] show_stack+0x10/0x1c
[<ffffffc000c6c698>] dump_stack+0x1c/0x28
[<ffffffc00021c95c>] warn_slowpath_common+0x74/0x9c
[<ffffffc00021c9d0>] warn_slowpath_fmt+0x4c/0x58
[<ffffffc000269d7c>] __enable_irq+0x70/0xc0
[<ffffffc000269e34>] enable_irq+0x68/0x7c
[<ffffffbffc0609b4>] arche_platform_probe+0x3b4/0x4f4 [gb_arche]
[<ffffffc0005ace30>] platform_drv_probe+0x14/0x20
[<ffffffc0005ab980>] driver_probe_device+0x160/0x374
[<ffffffc0005abc40>] __driver_attach+0x60/0x90
[<ffffffc0005aa768>] bus_for_each_dev+0x74/0x94
[<ffffffc0005ab2c4>] driver_attach+0x1c/0x28
[<ffffffc0005aae74>] bus_add_driver+0x124/0x248
[<ffffffc0005ac270>] driver_register+0x94/0x110
[<ffffffc0005ad3c4>] platform_driver_register+0x58/0x64
[<ffffffbffc065020>] $x+0x20/0x58 [gb_arche]
[<ffffffc0002007dc>] do_one_initcall+0xb0/0x14c
[<ffffffc00028252c>] load_module+0x19d0/0x1b18
[<ffffffc00028278c>] SyS_init_module+0x118/0x130
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Vaibhav Hiremath <vaibhav.hiermath@linaro.org>
Tested-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/arche-platform.c

@@ -603,7 +603,7 @@ static int arche_platform_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	arche_platform_wd_irq_en(arche_pdata);
+	gpio_direction_input(arche_pdata->wake_detect_gpio);
 
 	ret = device_create_file(dev, &dev_attr_state);
 	if (ret) {