lib: math: polynomial: remove link to non-exist file and fix spelling

lib: math: polynomial: remove link to non-exist file and fix spelling

The Baikal SoC and platform support was dropped from the kernel, remove
the reference to non-exist file.  While at it, fix spelling.

Link: https://lkml.kernel.org/r/20260302092831.2267785-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>