OPP: Fix -Wunsequenced in _of_add_opp_table_v1()

Clang warns (or errors with CONFIG_WERROR=y):

  drivers/opp/of.c:1081:28: error: multiple unsequenced modifications to 'val' [-Werror,-Wunsequenced]
   1081 |                         .freq = be32_to_cpup(val++) * 1000,
        |                                                 ^
   1082 |                         .u_volt = be32_to_cpup(val++),
        |                                                   ~~
  1 error generated.

There is no sequence point in a designated initializer. Move back to
separate variables for the creation of the values, so that there are
sequence points between each evaluation and increment of val.

Fixes: 75bbc92 ("OPP: Add dev_pm_opp_add_dynamic() to allow more flexibility")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Author: nathanchance

drivers/opp/of.c

@@ -1077,9 +1077,11 @@ static int _of_add_opp_table_v1(struct device *dev, struct opp_table *opp_table)
 
 	val = prop->value;
 	while (nr) {
+		unsigned long freq = be32_to_cpup(val++) * 1000;
+		unsigned long volt = be32_to_cpup(val++);
 		struct dev_pm_opp_data data = {
-			.freq = be32_to_cpup(val++) * 1000,
-			.u_volt = be32_to_cpup(val++),
+			.freq = freq,
+			.u_volt = volt,
 		};
 
 		ret = _opp_add_v1(opp_table, dev, &data, false);