kernel: add missing symbol for bcm27xx

When KERNEL_PERF_EVENTS is enabled in OpenWrt, the RPI_AXIPERF symbol is
exposed. Add a build option for it to fix build failures with
KERNEL_PERF_EVENTS enabled.

Fixes: 20ea6adbf199 ("bcm27xx: add support for linux v5.15")
Signed-off-by: Stijn Tintel <[email protected]>

config/Config-kernel.in

@@ -81,6 +81,11 @@ config KERNEL_PROFILING
 	  Enable the extended profiling support mechanisms used by profilers such
 	  as OProfile.
 
+config KERNEL_RPI_AXIPERF
+	bool "Compile the kernel with RaspberryPi AXI Performance monitors"
+	default y
+	depends on KERNEL_PERF_EVENTS
+
 config KERNEL_UBSAN
 	bool "Compile the kernel with undefined behaviour sanity checker"
 	help