Refactor and comment downloaded and compiled toolchains

Move the common parts of br-ext/configs/toolchain-aarch32-sdk and
br-ext/configs/toolchain-aarch64-sdk into
br-ext/configs/toolchain-common-sdk.
br-ext/configs/toolchain-aarch32-sdk was previously using
BR2_TOOLCHAIN_EXTERNAL_GCC_11=y and is now by using
br-ext/configs/toolchain-common-sdk updated to use the correct
BR2_TOOLCHAIN_EXTERNAL_GCC_14=y.

Add comments where to update if compiled or downloaded toolchain is
updated.

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
diff --git a/toolchain.mk b/toolchain.mk
index 4dc859a..342150d 100644
--- a/toolchain.mk
+++ b/toolchain.mk
@@ -57,11 +57,14 @@
 
 ifeq ($(UNAME_M),x86_64)
 ifeq ($(ARCH),arm)
+# Please keep in sync with br-ext/configs/toolchain-aarch32
+# and below for aarch64 host
 AARCH32_PATH 			?= $(TOOLCHAIN_ROOT)/aarch32
 AARCH32_CROSS_COMPILE 		?= $(AARCH32_PATH)/bin/arm-linux-gnueabihf-
 AARCH32_GCC_VERSION 		?= arm-gnu-toolchain-11.3.rel1-x86_64-arm-none-linux-gnueabihf
 SRC_AARCH32_GCC 		?= https://developer.arm.com/-/media/Files/downloads/gnu/11.3.rel1/binrel/$(AARCH32_GCC_VERSION).tar.xz
 
+# Please keep in sync with br-ext/configs/toolchain-aarch64
 AARCH64_PATH 			?= $(TOOLCHAIN_ROOT)/aarch64
 AARCH64_CROSS_COMPILE 		?= $(AARCH64_PATH)/bin/aarch64-linux-gnu-
 AARCH64_GCC_VERSION 		?= arm-gnu-toolchain-11.3.rel1-x86_64-aarch64-none-linux-gnu
@@ -116,6 +119,8 @@
 
 else ifeq ($(UNAME_M),aarch64)
 
+# Please keep in sync with br-ext/configs/toolchain-aarch32
+# and above for x86_64 host
 AARCH32_PATH 			?= $(TOOLCHAIN_ROOT)/aarch32
 AARCH32_CROSS_COMPILE 		?= $(AARCH32_PATH)/bin/arm-linux-gnueabihf-
 AARCH32_GCC_VERSION 		?= arm-gnu-toolchain-11.3.rel1-aarch64-arm-none-linux-gnueabihf