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.
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.