HOB: Busy cursor when saving configuration

Display a busy cursor while the configuration is saved.

[YOCTO #4846]
Signed-off-by: Valentin Popa <valentin.popa@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
lib/bb/monitordisk.py: fix spelling in error text

Signed-off-by: Erik Botö <erik.boto@pelagicore.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>