rust: Increase QEMU size to 1024 MB

rust: Increase QEMU size to 1024 MB

Rightnow rust depends on llvm instead of rust-llvm

Setup in rust-llvm
CFLAGS:remove = "-g"
CXXFLAGS:remove = "-g"

Setup in llvm
DEBUG_LEVELFLAG = "-g1"

As a result, the stage1 compiler crate binaries include debug symbols,
increasing their size. These binaries are used to run tests inside QEMU.
To accommodate this, increase the QEMU RAM allocation to 1024 MB.

Signed-off-by: Deepesh Varatharajan <Deepesh.Varatharajan@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>