kernel.h: split out kstrtox() and simple_strtox() to a separate header

stable inclusion
from stable-v5.10.185
commit 6e2e551e39fddda9a6c3385115368578c01d570e
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8L5XP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6e2e551e39fddda9a6c3385115368578c01d570e

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

[ Upstream commit 4c527293 ]

kernel.h is being used as a dump for all kinds of stuff for a long time.
Here is the attempt to start cleaning it up by splitting out kstrtox() and
simple_strtox() helpers.

At the same time convert users in header and lib folders to use new
header.  Though for time being include new header back to kernel.h to
avoid twisted indirected includes for existing users.

[andy.shevchenko@gmail.com: fix documentation references]
  Link: https://lkml.kernel.org/r/20210615220003.377901-1-andy.shevchenko@gmail.com

Link: https://lkml.kernel.org/r/20210611185815.44103-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Francis Laniel <laniel_francis@privacyrequired.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Kars Mulder <kerneldev@karsmulder.nl>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Anna Schumaker <anna.schumaker@netapp.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stable-dep-of: 4acfe3df ("test_firmware: prevent race conditions by a correct implementation of locking")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>