proc: make the proc_create[_data]() stubs static inlines

Change the proc_create[_data]() stubs which are used when CONFIG_PROC_FS
is not set from #defines to a static inline stubs.

This should fix clang -Werror builds failing due to errors like this:

  drivers/platform/x86/thinkpad_acpi.c:918:30: error: unused variable
   'dispatch_proc_ops' [-Werror,-Wunused-const-variable]

Fixing this in include/linux/proc_fs.h should ensure that the same issue
is also fixed in any other drivers hitting the same -Werror issue.

[akpm@linux-foundation.org: fix CONFIG_PROC_FS=n]
[akpm@linux-foundation.org: fix arch/sparc/kernel/led.c]
[akpm@linux-foundation.org: fix build]

Link: https://lkml.kernel.org/r/20211116131112.508304-1-hdegoede@redhat.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>