machine/badger2040: support for Badger 2040

Signed-off-by: deadprogram <ron@hybridgroup.com>

targets/badger2040.json

@@ -0,0 +1,11 @@
+{
+    "inherits": [
+        "rp2040"
+    ],
+    "serial": "uart",
+    "build-tags": ["badger2040"],
+    "linkerscript": "targets/badger2040.ld",
+    "extra-files": [
+        "targets/pico-boot-stage2.S"
+    ]
+}

targets/badger2040.ld

@@ -0,0 +1,10 @@
+
+MEMORY
+{
+    /* Reserve exactly 256 bytes at start of flash for second stage bootloader */
+    BOOT2_TEXT (rx) : ORIGIN = 0x10000000, LENGTH = 256
+    FLASH_TEXT (rx) : ORIGIN = 0x10000000 + 256, LENGTH = 1020K - 256
+    RAM (rwx)       : ORIGIN = 0x20000000, LENGTH = 256k
+}
+
+INCLUDE "targets/rp2040.ld"