bootloader: fix section placement issues found by the check script

Summary of changes:

- bootloader_clock split into *_clock_init and *_clock_loader.
  Only esp_clk_apb_freq is in *_clock_loader.
- bootloader_common moved out of loader; functions needed in loader
  (or, referenced from bootloader_utility) were moved into
  bootloader_common_loader.c.
- assert and abort moved into bootloader_panic, made part of the
  loader
- rtc_clk and rtc_time made part of loader

components/bootloader_support/src/bootloader_init.c

@@ -101,10 +101,3 @@ void bootloader_print_banner(void)
     ESP_LOGI(TAG, "ESP-IDF %s 2nd stage bootloader", IDF_VER);
     ESP_LOGI(TAG, "compile time " __TIME__);
 }
-
-void __assert_func(const char *file, int line, const char *func, const char *expr)
-{
-    ESP_LOGE(TAG, "Assert failed in %s, %s:%d (%s)", func, file, line, expr);
-    while (1) {
-    }
-}