efivars: Fix check for CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE

The 'CONFIG_' prefix is not implicit in IS_ENABLED().

Signed-off-by: Ben Hutchings <[e-mail]>
Cc: Seth Forshee <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Matt Fleming <[e-mail]>

drivers/firmware/efivars.c

···
 #define GUID_LEN 36
 
 static bool efivars_pstore_disable =
-	IS_ENABLED(EFI_VARS_PSTORE_DEFAULT_DISABLE);
+	IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);
 
 module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);