VIM3: add workaround to fix building mesa

[miksadikov]

When building Debian 11 for VIM3 with settings: _KHADAS_BOARD=VIM3 LINUX=mainline UBOOT=mainline DISTRIBUTION=Debian DISTRIB_RELEASE=bullseye DISTRIB_RELEASE_VERSION=11 DISTRIB_TYPE=xfce DISTRIB_ARCH=arm64 INSTALL_TYPE=SD-USB COMPRESSIMAGE=yes

the following build error occurs: Info: Building mesa... cp: cannot stat 'bullseye/arm64/*': No such file or directory make: *** [Makefile:2: all] Error 1

_echo $DISTRIBRELEASE bullseye

But directory bullseye/arm64/ is missing. Instead there is directory buster/arm64/. I suggest a temporary workaround :)

[miksadikov]

Solved here: VIM3: fix debian 11 build errors