ARM: 7390/1: dts: versatile-pb/ab fix MMC IRQs

The MMCI driver will not work without two IRQs since this is not
flagged as a single-irq variant. Looking through the complex IRQ
definition for the MMCI on the versatile (including an #if 1
statement forcing MMCI IRQ0 to the VIC) this appears to the the
correct IRQ number for both models.

Cc: Niklas Hernaeus <niklas.hernaeus@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>