[POWERPC] PS3: Fix setting bookmark in logical performance monitor

Fix the ps3_set_bookmark() routine of the PS3 logical performance
monitor driver.

To properly set a performance monitor bookmark the Cell processor
requires no instruction branches near the setting of the bookmark
SPR.  Testing showed that the use of the db10cyc instruction did
not work correctly.  This change replaces the db10cyc instruction
with 10 nop instructions.

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>