SPI: move instability warning to .cpp file

to avoid spamming build logs

Author: shadow578

libraries/SPI/src/SPI.cpp

@@ -3,6 +3,8 @@
 #include <drivers/gpio/gpio.h>
 #include <drivers/sysclock/sysclock.h>
 
+#warning "SPI on the HC32F460 has not been tested yet. See https://github.com/shadow578/framework-arduino-hc32f46x/pull/29" 
+
 /**
  * @brief given a integer v, round up to the next power of two
  * @note based on https://stackoverflow.com/a/466242

libraries/SPI/src/SPI.h

@@ -14,8 +14,6 @@
 #error "SPI library requires PWC DDL to be enabled"
 #endif
 
-#warning "SPI on the HC32F460 has not been tested yet. See https://github.com/shadow578/framework-arduino-hc32f46x/pull/29" 
-
 
 // SPI_HAS_TRANSACTION means SPI has
 //   - beginTransaction()