perf util: Remove unused perf_config__refresh

perf_config__refresh() was added in 2016 by
commit 8a0a9c7e9146 ("perf config: Introduce new init() and exit()")
but has remained unused.

Remove it.

Signed-off-by: Dr. David Alan Gilbert <[e-mail]>
Reviewed-by: Ian Rogers <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/util/config.c

···
 	config_set = NULL;
 }
 
-void perf_config__refresh(void)
-{
-	perf_config__exit();
-	perf_config__init();
-}
-
 static void perf_config_item__delete(struct perf_config_item *item)
 {
 	zfree(&item->name);

tools/perf/util/config.h

···
 int perf_config_set__collect(struct perf_config_set *set, const char *file_name,
 			     const char *var, const char *value);
 void perf_config__exit(void);
-void perf_config__refresh(void);
 int perf_config__set_variable(const char *var, const char *value);
 
 /**