esp32c3: add support for this chip

This change adds support for the ESP32-C3, a new chip from Espressif. It
is a RISC-V core so porting was comparatively easy.

Most peripherals are shared with the (original) ESP32 chip, but with
subtle differences. Also, the SVD file I've used gives some
peripherals/registers a different name which makes sharing code harder.
Eventually, when an official SVD file for the ESP32 is released, I
expect that a lot of code can be shared between the two chips.

More information: https://www.espressif.com/en/products/socs/esp32-c3

TODO:
  - stack scheduler
  - interrupts
  - most peripherals (SPI, I2C, PWM, etc)

1 files changed, 0 insertions, 0 deletions

diff --git a/lib/cmsis-svd b/lib/cmsis-svd
-Subproject 9c35b6d9df1f9eeecfcc33fc6f98719dbaaa30c
+Subproject df75ff974c76a911fc2815e29807f5ecaae06fc