drivers/rtc/rtc-da9055.c: remove use of regmap_irq_get_virq()

Using platform_get_irq_byname() to retrieve the IRQ number returns the
VIRQ number rather than the local IRQ number for the device.  Passing that
value then into regmap_irq_get_virq() causes a failure because the
function is expecting the local IRQ number (e.g.  0, 1, 2, 3, etc).

This patch removes use of regmap_irq_get_virq() to prevent this failure
from happening

Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>