hwmon: submitting-patches: Explain race conditions caused by calculations in macros

hwmon: submitting-patches: Explain race conditions caused by calculations in macros

The current documentation advises against calculations in macros
primarily to avoid code obfuscation. It misses the risk of concurrency
issues.

Add a note explaining that macros evaluating arguments multiple times
can lead to race conditions when accessing shared data.

Link: https://lore.kernel.org/all/CALbr=LYJ_ehtp53HXEVkSpYoub+XYSTU8Rg=o1xxMJ8=5z8B-g@mail.gmail.com/
Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com>
Link: https://lore.kernel.org/r/20251202175536.12774-1-hanguidong02@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>