Enable support for MIDI Host in arduino/ports/rp2040

[rppicomidi]

Fix #560

[rppicomidi]

@hathach Did my one line change in the src/arduino/ports/rp2040 directory break the esp32p4 build?

[MacGuffin-Underscore]

@hathach Did my one line change in the src/arduino/ports/rp2040 directory break the esp32p4 build?

I saw that PR#486 failed the same check, could be something else?

[rppicomidi]

Yes, it seems something else is wrong with the whole esp32p4 build. My pull request should not have caused this error, I believe. Every .ino file fails to build due to a bad CPUFreq option:

  Error during build: Invalid FQBN: getting build properties for board esp32:esp32:esp32p4: invalid option 'CPUFreq'
	mouse_ramdisk.ino ❌
mouse_ramdisk.ino esp32:esp32:esp32p4:JTAGAdapter=default,PSRAM=disabled,USBMode=default,CDCOnBoot=cdc,MSCOnBoot=default,DFUOnBoot=default,UploadMode=default,PartitionScheme=default,CPUFreq=360,FlashMode=qio,FlashFreq=80,FlashSize=4M,UploadSpeed=921600,DebugLevel=none,EraseFlash=none built output
  
  Error during build: Invalid FQBN: getting build properties for board esp32:esp32:esp32p4: invalid option 'CPUFreq'
	serial_host_bridge.ino ❌

[hathach]

thank you