[ARM] 4529/1: [HP Jornada 7XX] - Fix jornada720.c to use SSP driver

This fixes the jornada720.c file :

* ifdef for CONFIG_SA1100_JORNADA720_SSP since we dont want to include anything not selected in menyconfig.
* add documentation for init for future reference
* change platform driver name from jornada720_mcu ->
jornada_ssp.
* change maintainer in file.

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