firmware/ice40-riscv: Create a reboot() function

instead of direct access to registers.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: Iaee092c5ef651f0350b3f46386ed79fdbe06afcb
diff --git a/firmware/ice40-riscv/e1-tracer/misc.h b/firmware/ice40-riscv/e1-tracer/misc.h
index 31e8f80..ac942ec 100644
--- a/firmware/ice40-riscv/e1-tracer/misc.h
+++ b/firmware/ice40-riscv/e1-tracer/misc.h
@@ -13,3 +13,5 @@
 void vio_set(unsigned value);
 
 void e1_tick_read(uint16_t *ticks);
+
+void reboot(int fw);