fix usages of PsBufferAcc api

src/pystencils/backend/ast/analysis.py

src/pystencils/backend/kernelcreation/ast_factory.py

src/pystencils/backend/platforms/cuda.py

src/pystencils/backend/platforms/generic_cpu.py

src/pystencils/backend/platforms/sycl.py

src/pystencils/backend/platforms/x86.py