py: Add mp_raise_msg_varg helper and use it where appropriate.

This commit adds mp_raise_msg_varg(type, fmt, ...) as a helper for
nlr_raise(mp_obj_new_exception_msg_varg(type, fmt, ...)).  It makes the
C-level API for raising exceptions more consistent, and reduces code size
on most ports:

   bare-arm:   +28 +0.042%
minimal x86:  +100 +0.067%
   unix x64:   -56 -0.011%
unix nanbox:  -300 -0.068%
      stm32:  -204 -0.054% PYBV10
     cc3200:    +0 +0.000%
    esp8266:   -64 -0.010% GENERIC
      esp32:  -104 -0.007% GENERIC
        nrf:  -136 -0.094% pca10040
       samd:    +0 +0.000% ADAFRUIT_ITSYBITSY_M4_EXPRESS

2 files changed, 2 insertions, 2 deletions

diff --git a/ports/pic16bit/modpybled.c b/ports/pic16bit/modpybled.c
index 0d200c603..eb34865f2 100644
--- a/ports/pic16bit/modpybled.c
+++ b/ports/pic16bit/modpybled.c
@@ -50,7 +50,7 @@ STATIC mp_obj_t pyb_led_make_new(const mp_obj_type_t *type, size_t n_args, size_
     mp_arg_check_num(n_args, n_kw, 1, 1, false);
     mp_int_t led_id = mp_obj_get_int(args[0]);
     if (!(1 <= led_id && led_id <= NUM_LED)) {
-        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "LED %d does not exist", led_id));
+        mp_raise_msg_varg(&mp_type_ValueError, "LED %d does not exist", led_id);
     }
     return (mp_obj_t)&pyb_led_obj[led_id - 1];
 }
diff --git a/ports/pic16bit/modpybswitch.c b/ports/pic16bit/modpybswitch.c
index 0799ad9e8..924cce6ef 100644
--- a/ports/pic16bit/modpybswitch.c
+++ b/ports/pic16bit/modpybswitch.c
@@ -49,7 +49,7 @@ STATIC mp_obj_t pyb_switch_make_new(const mp_obj_type_t *type, size_t n_args, si
     mp_arg_check_num(n_args, n_kw, 1, 1, false);
     mp_int_t sw_id = mp_obj_get_int(args[0]);
     if (!(1 <= sw_id && sw_id <= NUM_SWITCH)) {
-        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "Switch %d does not exist", sw_id));
+        mp_raise_msg_varg(&mp_type_ValueError, "Switch %d does not exist", sw_id);
     }
     return (mp_obj_t)&pyb_switch_obj[sw_id - 1];
 }