linux-user/sparc: Use WREG constants in sparc/target_cpu.h

This fixes a naming bug wherein we used "UREG_FP" to access the
stack pointer.  OTOH, the "UREG_FP" constant was also defined
incorrectly such that it *did* reference the stack pointer.

Note that the kernel legitimately uses the name "FP", because it
utilizes the rolled stack window in processing the system call.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20191106113318.10226-5-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/sparc/target_cpu.h

@@ -41,15 +41,9 @@ static inline void cpu_set_tls(CPUSPARCState *env, target_ulong newtls)
     env->gregs[7] = newtls;
 }
 
-#ifndef UREG_I6
-#define UREG_I6        6
-#endif
-#ifndef UREG_FP
-#define UREG_FP        UREG_I6
-#endif
-
 static inline abi_ulong get_sp_from_cpustate(CPUSPARCState *state)
 {
-    return state->regwptr[UREG_FP];
+    return state->regwptr[WREG_SP];
 }
+
 #endif