nuttx: Add missing include header in IRQ implementation

Missing header became evident after a code refactor in another NuttX
component, which resulted in build warnings.

Signed-off-by: Gustavo Henrique Nihei <gustavo.nihei@espressif.com>

lib/system/nuttx/irq.c

@@ -12,6 +12,7 @@
 #include <metal/errno.h>
 #include <metal/irq_controller.h>
 #include <metal/alloc.h>
+#include <nuttx/arch.h>
 #include <nuttx/irq.h>
 
 unsigned int metal_irq_save_disable(void)