firmware: arm_scmi: prevent accessing rate_discrete uninitialized

gcc-5.3 and earlier warns that rate_discrete maybe-uninitialized
    ../drivers/firmware/arm_scmi/clock.c:185:5: warning: 'rate_discrete'
        may be used uninitialized in this function [-Wmaybe-uninitialized]
      if (rate_discrete)
         ^
    ../drivers/firmware/arm_scmi/clock.c:128:7: note:
        'rate_discrete' was declared here
      bool rate_discrete;
           ^
This patch fixing the warning by initialising rate_discrete and also using
goto label for the error path.

Fixes: 5f6c6430e904 ("firmware: arm_scmi: add initial support for clock protocol")
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
[sudeep.holla: added one line description to the commit message]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
index e8ffad3..e6f1782 100644
--- a/drivers/firmware/arm_scmi/clock.c
+++ b/drivers/firmware/arm_scmi/clock.c
@@ -125,7 +125,7 @@
 {
 	u64 *rate;
 	int ret, cnt;
-	bool rate_discrete;
+	bool rate_discrete = false;
 	u32 tot_rate_cnt = 0, rates_flag;
 	u16 num_returned, num_remaining;
 	struct scmi_xfer *t;
@@ -147,7 +147,7 @@
 
 		ret = scmi_do_xfer(handle, t);
 		if (ret)
-			break;
+			goto err;
 
 		rates_flag = le32_to_cpu(rlist->num_rates_flags);
 		num_remaining = NUM_REMAINING(rates_flag);
@@ -185,6 +185,7 @@
 	if (rate_discrete)
 		clk->list.num_rates = tot_rate_cnt;
 
+err:
 	scmi_one_xfer_put(handle, t);
 	return ret;
 }