[CELL] spufs: remove needless context save/restore code

The following steps are not needed in the SPE context save/restore
paths:

Save Step 12: save_mfc_decr()
  save suspend_time to CSA (It will be done by step 14)
  save ch 7 (decrementer value will be saved in LSCSA by spe-side step 10)

Restore Step 59: restore_ch_part1()
  restore ch 1 (it will be done by spe-side step 15)

This change removes the unnecessary steps.

Signed-off-by: Masato Noguchi <Masato.Noguchi@jp.sony.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>