common: migrate the deprecated --mmap/--no-mmap to --load-mode (#26934)

Replace the deprecated --mmap, --no-mmap, --mlock, and --direct-io flags with
the unified --load-mode argument across scripts, examples, and documentation.
Internal warning message and env var docs updated accordingly.

Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>

examples/sycl/run-llama2.sh

@@ -18,7 +18,7 @@ CONTEXT=4096
 #support malloc device memory more than 4GB.
 export UR_L0_ENABLE_RELAXED_ALLOCATION_LIMITS=1
 
-LOAD_MODE='--mmap'
+LOAD_MODE='--load-mode auto'
 if [ $# -gt 0 ]; then
     GGML_SYCL_DEVICE=$1
     echo "use $GGML_SYCL_DEVICE as main GPU"