Add reset_usb_boot ROM function typedef and wire it into
board_reset() so that 'nsh> reboot bootloader'
(BOARDIOC_SOFTRESETCAUSE_ENTER_BOOTLOADER) on RP2040 boards enters
BOOTSEL USB mass-storage mode directly, matching the behavior
already available on rp23xx boards. All other status values keep
the existing up_systemreset() behavior.
This affects all boards under boards/arm/rp2040/common (pico,
pico-w, feather-rp2040, xiao-rp2040, w5500-evb-pico, etc.) since
the change is in the shared board_reset() implementation.
Assisted-by: GitHubCopilot:claude-4.6-opus
Signed-off-by: wangjianyu3 <wangjianyu3@xiaomi.com>
71499bd66e