irqchip/gic-v3-its: Silence warning when its_lpi_alloc_chunks gets inlined

More agressive inlining in recent versions of GCC have uncovered
a new set of warnings:

 drivers/irqchip/irq-gic-v3-its.c: In function its_msi_prepare:
  drivers/irqchip/irq-gic-v3-its.c:1148:26: warning: lpi_base may be used
    uninitialized in this function [-Wmaybe-uninitialized]
     dev->event_map.lpi_base = lpi_base;
                          ^
 drivers/irqchip/irq-gic-v3-its.c:1116:6: note: lpi_base was declared here
  int lpi_base;
	      ^
 drivers/irqchip/irq-gic-v3-its.c:1149:25: warning: nr_lpis may be used
  uninitialized in this function [-Wmaybe-uninitialized]
   dev->event_map.nr_lpis = nr_lpis;
	                         ^
 drivers/irqchip/irq-gic-v3-its.c:1117:6: note: nr_lpis was declared here
  int nr_lpis;
	      ^
The warning is fairly benign (there is no code path that could
actually use uninitialized variables), but let's silence it anyway
by zeroing the variables on the error path.

Reported-by: Alex Shi <[email protected]>
Tested-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Cc: [email protected]
Cc: David Daney <[email protected]>
Cc: Jason Cooper <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

drivers/irqchip/irq-gic-v3-its.c

@@ -719,6 +719,9 @@ static unsigned long *its_lpi_alloc_chunks(int nr_irqs, int *base, int *nr_ids)
 out:
 	spin_unlock(&lpi_lock);
 
+	if (!bitmap)
+		*base = *nr_ids = 0;
+
 	return bitmap;
 }