ARM: OMAP2+: Fix omap3 prm shared irq

Shared interrupts with IRQ_NOAUTOEN got a warning added with commit
04c848d ("genirq: Warn when IRQ_NOAUTOEN is used with shared
interrupts").

Let's just drop the IRQ_NOAUTOEN use for omap3 PRM shared interrupt as
it does not seem to cause any other issues based on my testing. We have
moved a lot of the code to initialize later, and whatever problems the
legacy booting had seem to be gone now with pinctrl driver and device
tree based booting.

Otherwise we will get:

WARNING: CPU: 0 PID: 1 at kernel/irq/manage.c:1348 __setup_irq+0x5d0/0x64c
[<c01b0260>] (__setup_irq) from [<c01b0480>]
(request_threaded_irq+0xdc/0x188)
[<c01b0480>] (request_threaded_irq) from [<c051c780>]
(pcs_probe+0x6ec/0x8a4)
[<c051c780>] (pcs_probe) from [<c05a84b8>] (platform_drv_probe+0x50/0xb0)
[<c05a84b8>] (platform_drv_probe) from [<c05a6288>]
(driver_probe_device+0x33c/0x478)

Note that we also need to remove the related enable_irq() to avoid
getting the following:

WARNING: CPU: 0 PID: 1 at kernel/irq/manage.c:529 enable_irq+0x34/0x70
[<c01afa04>] (enable_irq) from [<c0c0f1fc>] (omap3_pm_init+0x118/0x3f8)
[<c0c0f1fc>] (omap3_pm_init) from [<c0c0ae7c>] (am35xx_init_late+0x10/0x18)

Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/pm34xx.c

@@ -486,7 +486,6 @@ int __init omap3_pm_init(void)
 	ret = request_irq(omap_prcm_event_to_irq("io"),
 		_prcm_int_handle_io, IRQF_SHARED | IRQF_NO_SUSPEND, "pm_io",
 		omap3_pm_init);
-	enable_irq(omap_prcm_event_to_irq("io"));
 
 	if (ret) {
 		pr_err("pm: Failed to request pm_io irq\n");

arch/arm/mach-omap2/prm3xxx.c

@@ -692,7 +692,6 @@ static int omap3xxx_prm_late_init(void)
 {
 	struct device_node *np;
 	int irq_num;
-	int ret;
 
 	if (!(prm_features & PRM_HAS_IO_WAKEUP))
 		return 0;
@@ -712,12 +711,8 @@ static int omap3xxx_prm_late_init(void)
 	}
 
 	omap3xxx_prm_enable_io_wakeup();
-	ret = omap_prcm_register_chain_handler(&omap3_prcm_irq_setup);
-	if (!ret)
-		irq_set_status_flags(omap_prcm_event_to_irq("io"),
-				     IRQ_NOAUTOEN);
 
-	return ret;
+	return omap_prcm_register_chain_handler(&omap3_prcm_irq_setup);
 }
 
 static void __exit omap3xxx_prm_exit(void)