machine/stm32: add STM32U585 target definition and runtime

Add processor target (cortex-m33), linker script (2048K flash, 768K RAM),
and arduino-uno-q board target. Runtime initializes 160MHz clock via PLL1
from HSI16, with PWR Range 1 and EPOD booster.

Also add psctype abstraction for timer PSC register width, needed because
the U5 SVD defines PSC as a 16-bit register.

targets/arduino-uno-q.json

@@ -0,0 +1,7 @@
+{
+  "inherits": ["stm32u585"],
+  "build-tags": ["arduino_uno_q"],
+  "serial": "uart",
+  "openocd-interface": "stlink",
+  "openocd-target": "stm32u5x"
+}

targets/stm32u585.json

@@ -0,0 +1,16 @@
+{
+  "inherits": [
+    "cortex-m33"
+  ],
+  "build-tags": [
+    "stm32u585",
+    "stm32u5",
+    "stm32"
+  ],
+  "extra-files": [
+    "src/device/stm32/stm32u585.s"
+  ],
+  "linkerscript": "targets/stm32u585.ld",
+  "flash-method": "openocd",
+  "openocd-target": "stm32u5x"
+}

targets/stm32u585.ld

@@ -0,0 +1,10 @@
+
+MEMORY
+{
+    FLASH_TEXT (rw) : ORIGIN = 0x08000000, LENGTH = 2048K
+    RAM (xrw)       : ORIGIN = 0x20000000, LENGTH = 768K
+}
+
+_stack_size = 4K;
+
+INCLUDE "targets/arm.ld"