uboot-phytec

log: Add log_nop() to avoid unused-variable warnings

If a log statement includes a variable and logging is disabled, this can
generate warnings about unused variables. Add a bit more complexity to the
macros to avoid this for the common case.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>