New NXP LPC32xx irq chip driver is used instead of a legacy one.

[this also fixes a harmless build warning about the NR_IRQS redefinition]
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Acked-by: Sylvain Lemieux <slemieux.tyco@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>