ARM: orion5x: remove extraneous NO_IRQ

rd88f6183ap-ge passes NO_IRQ as the interrupt line for its m25p80
NOR flash. However, this device never uses an interrupt and the
driver doesn't care, so we can simply remove the deprecated constant
here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>