ARM: Delete ARM11MPCore perf leftovers

My commit deleting the PB11MPCore apparently left a few dangling
structs in the perf event code. Fix it up.

Fixes: 2560cffd

 ("ARM: Delete ARM11MPCore (ARM11 ARMv6K SMP) support")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://lore.kernel.org/r/20231224-drop-11mpcore-fix-v1-1-d8b16d1c1fae@linaro.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>