utils: Add option to run root shell on console

Until I develop a captive portal-based mechanism for initially
configuring the WiFi on Raspberry Pi machines, the easiest way to do
initial provisioning is using the CLI via the serial console.  Since the
root account has no password, and I don't want to have to specify one in
downstream projects' configurations, I've added a configuration option
to enable automatically launching a root shell connected to the serial
console instead of a login prompt.  The security risks here are pretty
minimal, because someone would need phyiscal access to the device in
order to use this shell, in which case they could use any number of
other methods to get control of the system.

package/aimee-os-utils/Config.in

@@ -8,3 +8,25 @@ config BR2_PACKAGE_AIMEE_OS_UTILS
     select BR2_PACKAGE_UTIL_LINUX_SWITCH_ROOT
     select BR2_PACKAGE_WGET
     select BR2_TARGET_GRUB2_INSTALL_TOOLS
+
+if BR2_PACKAGE_AIMEE_OS_UTILS
+
+config AIMEE_OS_ROOT_SHELL
+    bool "Spawn a root shell on the serial console by default"
+    help
+      With this option enabled, the system will boot up normally, with
+      a root shell connected to the default serial console.  This is
+      useful for initial provisioning and troubleshooting.
+
+if AIMEE_OS_ROOT_SHELL
+
+config AIMEE_OS_ROOT_SHELL_CONSOLE
+    string "Console name"
+    default ttyAMA0
+    help
+      Name of the console device where the root shell will be spawned.
+      Do not include the /dev prefix
+
+endif
+
+endif