stm32/main: Reorder some init calls to put them before soft-reset loop.

The calls to rtc_init_start(), sdcard_init() and storage_init() are all
guarded by a check for first_soft_reset, so it's simpler to just put them
all before the soft-reset loop, without the check.

The call to machine_init() can also go before the soft-reset loop because
it is only needed to check the reset cause which can happen once at the
first boot.  To allow this to work, the reset cause must be set to SOFT
upon a soft-reset, which is the role of the new function machine_deinit().

ports/stm32/main.c

@@ -454,13 +454,21 @@ int main(void) {
     #endif
     pendsv_init();
     led_init();
-#if MICROPY_HW_HAS_SWITCH
+    #if MICROPY_HW_HAS_SWITCH
     switch_init0();
-#endif
+    #endif
+    machine_init();
+    #if MICROPY_HW_ENABLE_RTC
+    rtc_init_start(false);
+    #endif
     spi_init0();
     #if MICROPY_HW_ENABLE_HW_I2C
     i2c_init0();
     #endif
+    #if MICROPY_HW_HAS_SDCARD
+    sdcard_init();
+    #endif
+    storage_init();
 
 #if defined(USE_DEVICE_MODE)
     // default to internal flash being the usb medium
@@ -483,24 +491,6 @@ soft_reset:
     led_state(4, 0);
     uint reset_mode = update_reset_mode(1);
 
-    machine_init();
-
-#if MICROPY_HW_ENABLE_RTC
-    if (first_soft_reset) {
-        rtc_init_start(false);
-    }
-#endif
-
-    // more sub-system init
-#if MICROPY_HW_HAS_SDCARD
-    if (first_soft_reset) {
-        sdcard_init();
-    }
-#endif
-    if (first_soft_reset) {
-        storage_init();
-    }
-
     // Python threading init
     #if MICROPY_PY_THREAD
     mp_thread_init();
@@ -692,6 +682,7 @@ soft_reset_exit:
 #if MICROPY_HW_ENABLE_CAN
     can_deinit();
 #endif
+    machine_deinit();
 
     #if MICROPY_PY_THREAD
     pyb_thread_deinit();

ports/stm32/modmachine.c

@@ -99,6 +99,11 @@ void machine_init(void) {
     RCC->CSR |= RCC_CSR_RMVF;
 }
 
+void machine_deinit(void) {
+    // we are doing a soft-reset so change the reset_cause
+    reset_cause = PYB_RESET_SOFT;
+}
+
 // machine.info([dump_alloc_table])
 // Print out lots of information about the board.
 STATIC mp_obj_t machine_info(size_t n_args, const mp_obj_t *args) {

ports/stm32/modmachine.h

@@ -29,6 +29,7 @@
 #include "py/obj.h"
 
 void machine_init(void);
+void machine_deinit(void);
 
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_info_obj);
 MP_DECLARE_CONST_FUN_OBJ_0(machine_unique_id_obj);