PCI: rcar: Do not shadow the 'irq' variable

PCI: rcar: Do not shadow the 'irq' variable

The sparse tool rightfully detects:
drivers/pci/controller/pcie-rcar.c:741:30: warning: symbol 'irq' shadows an earlier one

Fix it now to avoid future surprises and for good coding style.

No functional change intended.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[lorenzo.pieralisi@arm.com: commit log refactoring]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>