[BUG] Building raspberrypi-pico using Makefile without export PICO_SDK_PATH generates not working binary

### Description / Steps to reproduce the issue

$ ./tools/configure.sh raspberrypi-pico:usbnsh
$ make

Copy nuttx.uf2 to RPI-RP2 virtual disk (that show up when connecting the USB cable with BOOTSEL button pressed). The image will not work (the board LED will not turn on and the USB Console will not appear)

### On which OS does this issue occur?

[OS: Linux]

### What is the version of your OS?

Ubuntu 24.04

### NuttX Version

mainline

### Issue Architecture

[Arch: all], [Arch: arm]

### Issue Area

[Area: Build System]

### Host information

_No response_

### Verification

- [x] I have verified before submitting the report.