[adc] Fix PICO_VSYS_PIN compile error on RP2350 boards (#14724)

tests/test_build_components/build_components_base.rp2040-pico2-ard.yaml

@@ -0,0 +1,15 @@
+esphome:
+  name: componenttestrp2040pico2ard
+  friendly_name: $component_name
+
+rp2040:
+  board: rpipico2
+
+logger:
+  level: VERY_VERBOSE
+
+packages:
+  component_under_test: !include
+    file: $component_test_file
+    vars:
+      component_test_file: $component_test_file

tests/test_build_components/common/spi/rp2040-pico2-ard.yaml

@@ -0,0 +1,12 @@
+# Common SPI configuration for RP2040 Pico 2 (RP2350) Arduino tests
+
+substitutions:
+  clk_pin: GPIO18
+  mosi_pin: GPIO19
+  miso_pin: GPIO16
+
+spi:
+  - id: spi_bus
+    clk_pin: ${clk_pin}
+    mosi_pin: ${mosi_pin}
+    miso_pin: ${miso_pin}