staging: ipack: Rename IPACK_MEM_SPACE to IPACK_MEM8_SPACE.

There also is a MEM16 space.  This will make it clear which one is
which, once support for MEM16 space is added.

Signed-off-by: Jens Taprogge <jens.taprogge@taprogge.org>
Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>