The static IRQ base is not used on any platforms with this chip
(only Ux500). Get rid of it forever, and rely on dynamic IRQ
descriptor allocation.

Cc: Samuel Ortiz <sameo@linux.intel.com>
Cc: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>