Fix multiple issues reported by Coverity Scan

fusee/fusee-primary/src/sdmmc/sdmmc.c

@@ -643,7 +643,7 @@ static int sdmmc_sd_switch(sdmmc_device_t *device, uint32_t mode, uint32_t group
 static int sdmmc_sd_set_current_limit(sdmmc_device_t *device, uint8_t *status)
 {
     /* Start with the highest possible limit. */
-    uint32_t current_limit = SD_SET_CURRENT_LIMIT_800;
+    int32_t current_limit = SD_SET_CURRENT_LIMIT_800;
     
     /* Try each limit. */
     while (current_limit > SD_SET_CURRENT_NO_CHANGE)

fusee/fusee-primary/src/stage2.c

@@ -110,5 +110,6 @@ void load_stage2(const char *bct0) {
     g_chainloader_entries[0].num          = 0;
     g_chainloader_entrypoint              = config.entrypoint;
 
-    strncpy(g_stage2_path, config.path, sizeof(g_stage2_path));
+    strncpy(g_stage2_path, config.path, sizeof(g_stage2_path) - 1);
+    g_stage2_path[sizeof(g_stage2_path) - 1]  = '\0';
 }