Add RP2350-only flash functions to Doxygen output (#3088)

src/rp2_common/hardware_flash/include/hardware/flash.h

diff --git a/src/rp2_common/hardware_flash/include/hardware/flash.h b/src/rp2_common/hardware_flash/include/hardware/flash.h
index 137ab9f..1fb943a 100644
--- a/src/rp2_common/hardware_flash/include/hardware/flash.h
+++ b/src/rp2_common/hardware_flash/include/hardware/flash.h
@@ -169,7 +169,7 @@
 
 void flash_flush_cache(void);
 
-#if !PICO_RP2040
+#if !PICO_RP2040 || PICO_COMBINED_DOCS
 typedef void (*qmi_setup_function_t)(void);
 
 /*! \brief Set the function to be called to setup the QMI CS1 configuration
@@ -303,7 +303,7 @@
  */
 void flash_devinfo_set_cs_gpio(uint cs, uint gpio);
 
-#endif // !PICO_RP2040
+#endif // !PICO_RP2040 || PICO_COMBINED_DOCS
 
 #ifdef __cplusplus
 }