MIPS: IP22: Use a generic method for irq statistics

MIPS: IP22: Use a generic method for irq statistics

The structure 'struct kernel_stat' defines the 'irqs' array as its field
only when CONFIG_GENERIC_HARDIRQS is not set. However, the ip22 code makes
use of this field unconditionally. As the result, the following build error
is produced:

  CC      arch/mips/sgi-ip22/ip22-int.o
arch/mips/sgi-ip22/ip22-int.c: In function 'indy_buserror_irq':
arch/mips/sgi-ip22/ip22-int.c:158: error: 'struct kernel_stat' has no
member named 'irqs'
make[1]: *** [arch/mips/sgi-ip22/ip22-int.o] Error 1
make: *** [arch/mips/sgi-ip22] Error 2

This patch fixes the build error by using the generic method for the irq
statistics.

Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@movial.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>