irqchip/stm32-exti: Mark events reserved with RIF configuration check

EXTI events availability depends on Resource Isolation Framework (RIF)
configuration.

RIF grants access to buses with Compartment ID (CID) filtering, secure and
privilege level. It also assigns EXTI events to one or several processors
(CID, Secure, Privilege).

EXTI events used by Linux must be CID-filtered (EnCIDCFGR.CFEN=1) and
statically assigned to CID1 (EnCIDCFR.CID=CID1).

EXTI events not filling these conditions are marked as reserved and can't
be used by Linux.

Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240415134926.1254428-7-antonio.borneo@foss.st.com