Add Bonsai C4 as a platform board file (#18901)

* Set up Bonsai C4 as a platform board file

* corrections and improvements based on testing and feedback

* Added VBUS sensing as default capability for improved split support using Bonsai C4

* Update clock divisor for SPI flash

Co-authored-by: Nick Brassel <nick@tzarc.org>

Co-authored-by: Nick Brassel <nick@tzarc.org>

platforms/chibios/boards/BONSAI_C4/configs/halconf.h

@@ -0,0 +1,49 @@
+/* Copyright 2022 David Hoelscher, customMK
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#ifndef HAL_USE_SPI
+#    define HAL_USE_SPI TRUE
+#endif
+
+#ifndef HAL_USE_I2C
+#    define HAL_USE_I2C TRUE
+#endif
+
+#ifdef SPLIT_KEYBOARD
+#    ifndef HAL_USE_SERIAL
+#        define HAL_USE_SERIAL TRUE
+#    endif
+#    ifndef SERIAL_BUFFERS_SIZE
+#        define SERIAL_BUFFERS_SIZE 256
+#    endif
+#endif
+
+#ifdef WS2812_DRIVER_PWM
+#    ifndef HAL_USE_PWM
+#        define HAL_USE_PWM TRUE
+#    endif
+#endif
+
+#ifndef SPI_SELECT_MODE
+#    define SPI_SELECT_MODE SPI_SELECT_MODE_PAD
+#endif
+
+#ifndef SPI_USE_WAIT
+#    define SPI_USE_WAIT TRUE
+#endif
+
+#include_next <halconf.h>