The IRQ support for SCH GPIO is not specific to the Intel Quark SoC.
Moreover the IRQ routing is quite interesting there, so while it's
needs a special support, the driver haven't it anyway yet.

Due to above remove basically redundant code of IRQ support.

This reverts commit ec689a8a.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>