stm32/pyb_i2c: Put pyb.I2C under MICROPY_PY_PYB_LEGACY setting.

When disabled, the pyb.I2C class saves around 8k of code space and 172
bytes of RAM.  The same functionality is now available in machine.I2C
(for F4 and F7 MCUs).

It is still enabled by default.

ports/stm32/main.c

@@ -505,7 +505,7 @@ void stm32_main(uint32_t reset_mode) {
     rtc_init_start(false);
     #endif
     spi_init0();
-    #if MICROPY_HW_ENABLE_HW_I2C
+    #if MICROPY_PY_PYB_LEGACY && MICROPY_HW_ENABLE_HW_I2C
     i2c_init0();
     #endif
     #if MICROPY_HW_HAS_SDCARD

ports/stm32/modpyb.c

@@ -227,7 +227,7 @@ STATIC const mp_rom_map_elem_t pyb_module_globals_table[] = {
 #if defined(MICROPY_HW_LED1)
     { MP_ROM_QSTR(MP_QSTR_LED), MP_ROM_PTR(&pyb_led_type) },
 #endif
-    #if MICROPY_HW_ENABLE_HW_I2C
+    #if MICROPY_PY_PYB_LEGACY && MICROPY_HW_ENABLE_HW_I2C
     { MP_ROM_QSTR(MP_QSTR_I2C), MP_ROM_PTR(&pyb_i2c_type) },
     #endif
     { MP_ROM_QSTR(MP_QSTR_SPI), MP_ROM_PTR(&pyb_spi_type) },

ports/stm32/pyb_i2c.c

@@ -35,7 +35,7 @@
 #include "dma.h"
 #include "i2c.h"
 
-#if MICROPY_HW_ENABLE_HW_I2C
+#if MICROPY_PY_PYB_LEGACY && MICROPY_HW_ENABLE_HW_I2C
 
 /// \moduleref pyb
 /// \class I2C - a two-wire serial protocol
@@ -1065,4 +1065,4 @@ const mp_obj_type_t pyb_i2c_type = {
     .locals_dict = (mp_obj_dict_t*)&pyb_i2c_locals_dict,
 };
 
-#endif // MICROPY_HW_ENABLE_HW_I2C
+#endif // MICROPY_PY_PYB_LEGACY && MICROPY_HW_ENABLE_HW_I2C

ports/stm32/stm32_it.c

@@ -776,6 +776,8 @@ void CAN2_SCE_IRQHandler(void) {
 }
 #endif
 
+#if MICROPY_PY_PYB_LEGACY
+
 #if defined(MICROPY_HW_I2C1_SCL)
 void I2C1_EV_IRQHandler(void) {
     IRQ_ENTER(I2C1_EV_IRQn);
@@ -831,3 +833,5 @@ void I2C4_ER_IRQHandler(void) {
     IRQ_EXIT(I2C4_ER_IRQn);
 }
 #endif // defined(MICROPY_HW_I2C4_SCL)
+
+#endif // MICROPY_PY_PYB_LEGACY