regmap: maple: Workaround for another false-positive compiler warning

Similar to the issue fixed in commit 542440f ("regmap: maple: work
around gcc-14.1 false-positive warning"), I see an uninitialized warning
for upper_index and upper_last.

Happens with arc-linux-gnu-gcc (Debian 15.3.0-1) 15.3.0 on an
allmodconfig for ARCH=arc.

Signed-off-by: Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com>
Link: https://patch.msgid.link/20260626060427.2548578-2-u.kleine-koenig@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: ukleinek

drivers/base/regmap/regcache-maple.c

@@ -112,7 +112,7 @@ static int regcache_maple_drop(struct regmap *map, unsigned int min,
 	unsigned long *entry, *lower, *upper;
 	/* initialized to work around false-positive -Wuninitialized warning */
 	unsigned long lower_index = 0, lower_last = 0;
-	unsigned long upper_index, upper_last;
+	unsigned long upper_index = 0, upper_last = 0;
 	int ret = 0;
 
 	lower = NULL;