drivers: interrupt_controller: add LiteX interrupt controller driver

Add LiteX interrupt controller driver and bindings for this device.

Signed-off-by: Filip Kokosinski <fkokosinski@internships.antmicro.com>
Signed-off-by: Mateusz Holenko <mholenko@antmicro.com>
diff --git a/drivers/interrupt_controller/Kconfig b/drivers/interrupt_controller/Kconfig
index 3266561..80201e8 100644
--- a/drivers/interrupt_controller/Kconfig
+++ b/drivers/interrupt_controller/Kconfig
@@ -119,6 +119,12 @@
 	  Platform Level Interrupt Controller provides support
 	  for external interrupt lines defined by the RISC-V SoC;
 
+config VEXRISCV_LITEX_IRQ
+	bool "VexRiscv LiteX Interrupt controller"
+	depends on SOC_RISCV32_LITEX_VEXRISCV
+	help
+	  IRQ implementation for LiteX VexRiscv
+
 config DW_ICTL
 	bool "Designware Interrupt Controller"
 	depends on MULTI_LEVEL_INTERRUPTS