[ARM] ecard: Convert card type enum to a flag

'type' in the struct expansion_card is only used to indicate
whether this card is an EASI card or not.  Therefore, having
it as an enum is wasteful (and introduces additional noise
when we come to remove the enum.)  Convert it to a mere flag
instead.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>