linux-user: fix microblaze get_sp_from_cpustate()

get_sigframe() uses regs[1] and this is actual SP.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20180409115212.875-1-laurent@vivier.eu>
diff --git a/linux-user/microblaze/target_signal.h b/linux-user/microblaze/target_signal.h
index de2b0f4..642865f 100644
--- a/linux-user/microblaze/target_signal.h
+++ b/linux-user/microblaze/target_signal.h
@@ -23,7 +23,7 @@
 
 static inline abi_ulong get_sp_from_cpustate(CPUMBState *state)
 {
-    return state->regs[14];
+    return state->regs[1];
 }