mfd: twl-core.c: Fix the number of interrupts managed by twl4030

TWL4030 does handle 3 different interrupts ranges: 8 for the core, 8 for
the power events and 18 for the GPIOs.

Change the total number of interrupts managed by TWL4030 from 8 to 34.

Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>