[POWERPC] PS3: Add ps3_get_speid routine

Add a new routine ps3_get_speid() which returns the logical
SPE ID.  This ID is needed for profiling support.

Signed-off-by: Takashi Yamamoto <TakashiA.Yamamoto@jp.sony.com>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>