NFC: st-nci: Disable irq when powering the device up

Upon some conditions (timing, CLF errors, platform errors...), the
irq might be already active when powering the device.

Add irq_active variable as a guard to avoid kernel warning message

Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>