Documentation: core-api: Drop :export: for int_log.h

The :export: keyword makes sense only for C-files, where EXPORT_SYMBOL()
might appear. Otherwise kernel-doc may not produce anything out of this
file.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: f97fa3dc ("lib/math: Move dvb_math.c into lib/math/int_log.c")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230725104956.47806-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>