i2c: core: add api to provide frequency mode strings

mainline inclusion
from mainline-v5.13-rc1
commit 3b4c747c
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I42E7E


CVE: NA

---------------------------

Some I2C drivers like Designware and HiSilicon will print the
bus frequency mode information, so add a public one that everyone
can make use of.

Add the definition of the I2C Frequency Modes macro.

Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Jiaran Zhang <zhangjiaran@huawei.com>
Reviewed-by: Sheng Feng &lt; <fengsheng5@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>