ARM: S3C24XX: Correct NR_IRQS definition for s3c2440

Due to NR_IRQS being incorrectly defined not all IRQ domains can
be registered for S3C2440. It causes following errors on a s3c2440
SoC based board:

NR_IRQS:89
S3C2440: IRQ Support
irq: clearing pending status 00000002
------------[ cut here ]------------
WARNING: at kernel/irq/irqdomain.c:234 0xc0056ed0()
...
irq: could not create irq-domain
...
s3c2410-wdt s3c2410-wdt: failed to install irq (-22)
s3c2410-wdt: probe of s3c2410-wdt failed with error -22
...
samsung-uart s3c2440-uart.0: cannot get irq 74

Fix this by increasing NR_IRQS to at least (IRQ_S3C2443_AC97 + 1)
if CPU_S3C2440 is selected, so the subintc IRQ domain gets properly
registered.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>