kernel: add missing dependency to KERNEL_RPI_AXIPERF
This symbol is added by the bcm27xx target patches so it should depend
on that target.
Fixes: efd9463dcfe2 ("kernel: add missing symbol for bcm27xx")
Signed-off-by: Stijn Tintel <[email protected]>
(cherry picked from commit d5dc6cdc536277ce1831acce92dc1cbdc59e7250)