ARM: 7128/1: vic: Don't write to the read-only register VIC_IRQ_STATUS

This is unneeded and causes an abort on the SPMP8000 platform.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Zoltan Devai <zoss@devai.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>