arm: spl: For Falcon Mode, set a default machid of ~0

arm: spl: For Falcon Mode, set a default machid of ~0

With device trees, boards do not always set CONFIG_MACH_TYPE now, so we
must not rely on this define being set.  The kernel uses ~0 to see if we
have a valid machine number or not, so set that as the default, invalid
machine, id and only fix if CONFIG_MACH_TYPE is set.

Acked-by: Dan Murphy <[email protected]>
Tested-by: Heiko Schocher <[email protected]>
Cc: Albert ARIBAUD <[email protected]>
Signed-off-by: Tom Rini <[email protected]>