genirq: Prevent [devm_]irq_alloc_desc from returning irq 0

Since commit a85a6c86 ("driver core: platform: Clarify that IRQ 0
is invalid"), having a linux-irq with number 0 will trigger a WARN()
when calling platform_get_irq*() to retrieve that linux-irq.

Since [devm_]irq_alloc_desc allocs a single irq and since irq 0 is not used
on some systems, it can return 0, triggering that WARN(). This happens
e.g. on Intel Bay Trail and Cherry Trail devices using the LPE audio engine
for HDMI audio:

 0 is an invalid IRQ number
 WARNING: CPU: 3 PID: 472 at drivers/base/platform.c:238 platform_get_irq_optional+0x108/0x180
 Modules linked in: snd_hdmi_lpe_audio(+) ...

 Call Trace:
  platform_get_irq+0x17/0x30
  hdmi_lpe_audio_probe+0x4a/0x6c0 [snd_hdmi_lpe_audio]

 ---[ end trace ceece38854223a0b ]---

Change the 'from' parameter passed to __[devm_]irq_alloc_descs() by the
[devm_]irq_alloc_desc macros from 0 to 1, so that these macros will no
longer return 0.

Fixes: a85a6c86 ("driver core: platform: Clarify that IRQ 0 is invalid")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201221185647.226146-1-hdegoede@redhat.com

include/linux/irq.h

@@ -928,7 +928,7 @@ int __devm_irq_alloc_descs(struct device *dev, int irq, unsigned int from,
 	__irq_alloc_descs(irq, from, cnt, node, THIS_MODULE, NULL)
 
 #define irq_alloc_desc(node)			\
-	irq_alloc_descs(-1, 0, 1, node)
+	irq_alloc_descs(-1, 1, 1, node)
 
 #define irq_alloc_desc_at(at, node)		\
 	irq_alloc_descs(at, at, 1, node)
@@ -943,7 +943,7 @@ int __devm_irq_alloc_descs(struct device *dev, int irq, unsigned int from,
 	__devm_irq_alloc_descs(dev, irq, from, cnt, node, THIS_MODULE, NULL)
 
 #define devm_irq_alloc_desc(dev, node)				\
-	devm_irq_alloc_descs(dev, -1, 0, 1, node)
+	devm_irq_alloc_descs(dev, -1, 1, 1, node)
 
 #define devm_irq_alloc_desc_at(dev, at, node)			\
 	devm_irq_alloc_descs(dev, at, at, 1, node)