efi_loader: move dtbdump.c, initrddump.c to lib/efi_loader

The tools dtbdump.efi and initrddump.efi are useful for Python testing even
if CONFIG_EFI_SELFTEST=n.

Don't clear the screen as it is incompatible with Python testing.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>