When CONFIG_CMDLINE_OVERRIDE or CONFIG_CMDLINE_FORCE are configured, the
command line provided by the boot stack should be ignored, and only the
built-in command line should be taken into account.
Add the required handling of this when dealing with initrd= or dtb=
command line options in the EFI stub.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>