staging: most: hdm-dim2: rename function

This patch renames the function dim_service_irq. It subsitutes the name
with the more suitable identifier dim_service_ahb_int_irq.

Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>