Battery (Linux): remove option --battery-dir

It was added in c5c3cecb93 but there was no comment or issues linked to indicate why it was necessary.

`/sys/class/power_supply` is standardized in <https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-class-power>. I don't I want to support non-standard platform unless proper reason is given

src/modules/battery/battery.c

@@ -115,14 +115,6 @@ bool ffParseBatteryCommandOptions(FFBatteryOptions* options, const char* key, co
         return true;
     }
 
-    #ifdef __linux__
-        if (ffStrEqualsIgnCase(subKey, "dir"))
-        {
-            ffOptionParseString(key, value, &options->dir);
-            return true;
-        }
-    #endif
-
     #ifdef _WIN32
         if (ffStrEqualsIgnCase(subKey, "use-setup-api"))
         {
@@ -147,14 +139,6 @@ void ffParseBatteryJsonObject(FFBatteryOptions* options, yyjson_val* module)
         if (ffJsonConfigParseModuleArgs(key, val, &options->moduleArgs))
             continue;
 
-        #ifdef __linux__
-        if (ffStrEqualsIgnCase(key, "dir"))
-        {
-            ffStrbufSetS(&options->dir, yyjson_get_str(val));
-            continue;
-        }
-        #endif
-
         #ifdef _WIN32
         if (ffStrEqualsIgnCase(key, "useSetupApi"))
         {
@@ -180,11 +164,6 @@ void ffGenerateBatteryJsonConfig(FFBatteryOptions* options, yyjson_mut_doc* doc,
 
     ffJsonConfigGenerateModuleArgsConfig(doc, module, &defaultOptions.moduleArgs, &options->moduleArgs);
 
-    #ifdef __linux__
-    if (!ffStrbufEqual(&defaultOptions.dir, &options->dir))
-        yyjson_mut_obj_add_strbuf(doc, module, "dir", &options->dir);
-    #endif
-
     #ifdef _WIN32
     if (defaultOptions.useSetupApi != options->useSetupApi)
         yyjson_mut_obj_add_bool(doc, module, "useSetupApi", options->useSetupApi);
@@ -257,9 +236,7 @@ void ffInitBatteryOptions(FFBatteryOptions* options)
     ffOptionInitModuleArg(&options->moduleArgs);
     options->temp = false;
 
-    #ifdef __linux__
-        ffStrbufInitStatic(&options->dir, "/sys/class/power_supply/");
-    #elif defined(_WIN32)
+    #ifdef _WIN32
         options->useSetupApi = false;
     #endif
 }
@@ -267,8 +244,4 @@ void ffInitBatteryOptions(FFBatteryOptions* options)
 void ffDestroyBatteryOptions(FFBatteryOptions* options)
 {
     ffOptionDestroyModuleArg(&options->moduleArgs);
-
-    #ifdef __linux__
-        ffStrbufDestroy(&options->dir);
-    #endif
 }

src/modules/battery/option.h

@@ -11,9 +11,7 @@ typedef struct FFBatteryOptions
 
     bool temp;
 
-    #ifdef __linux__
-        FFstrbuf dir;
-    #elif defined(_WIN32)
+    #ifdef _WIN32
         bool useSetupApi;
     #endif
 } FFBatteryOptions;