ath25: add missed HAVE_IRQ_EXIT_ON_IRQ_STACK

Add HAVE_IRQ_EXIT_ON_IRQ_STACK kernel configuration symbol that was
missed during backporting separate IRQ stack for MIPS from upstream.

Signed-off-by: Sergey Ryazanov <[email protected]>

target/linux/ath25/config-4.9

@@ -79,6 +79,7 @@ CONFIG_HAVE_FUNCTION_GRAPH_TRACER=y
 CONFIG_HAVE_FUNCTION_TRACER=y
 CONFIG_HAVE_GENERIC_DMA_COHERENT=y
 CONFIG_HAVE_IDE=y
+CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK=y
 CONFIG_HAVE_IRQ_TIME_ACCOUNTING=y
 CONFIG_HAVE_LATENCYTOP_SUPPORT=y
 CONFIG_HAVE_MEMBLOCK=y