mailbox: zynqmp-ipi: Fix SGI cleanup on unbind

The driver incorrectly determines SGI vs SPI interrupts by checking IRQ
number < 16, which fails with dynamic IRQ allocation. During unbind,
this causes improper SGI cleanup leading to kernel crash.

Add explicit irq_type field to pdata for reliable identification of SGI
interrupts (type-2) and only clean up SGI resources when appropriate.

Fixes: 6ffb1635 ("mailbox: zynqmp: handle SGI for shared IPI")
Signed-off-by: Harini T <harini.t@amd.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>