[PATCH] Serial: disable jsm in ppc64 defconfig

Changes to the serial driver to remove flip buffers have broken the serial
jsm driver.  It doesn't even compile anymore.  The jsm driver was enabled
in only one defconfig - ppc64.  In order to keep defconfigs building,
disable CONFIG_SERIAL_JSM for the time being.

Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>