NFC: st-nci: Get rid of "interesting" use of interrupt polarity

I2C and SPI frameworks followed by IRQ framework do set
interrupt polarity correctly if it's properly specified in firmware
(ACPI or DT).

Get rid of the redundant trick when requesting interrupt.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>