arm64: Kconfig.platforms: Add comments

Add trailing comments to endmenu statements for better readability.
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Link: https://lore.kernel.org/r/20220517141648.331976-3-juergh@canonical.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/Kconfig.platforms

@@ -325,4 +325,4 @@ config ARCH_ZYNQMP
 	help
 	  This enables support for Xilinx ZynqMP Family
 
-endmenu
+endmenu # "Platform selection"