lima: call lima_bo_va_unmap when freeing bo

Created by: anarsoul

Otherwise we'll get 'lima vm map va overlap' error from kernel if another bo takes va of freed bo

That fixes 'lima vm map va overlap' issue with glmark2-es-drm and now I'm hitting following assertion: glmark2-es2-drm: lima_draw.c:1066: lima_flush: Assertion `ctx->buffer_state[lima_ctx_buff_sh_varying].offset + ctx->buffer_state[lima_ctx_buff_sh_varying].size <= sh_gl_pos_offset - sh_varying_offset' failed.

Looks like we need dynamic buffer allocation.