kobject: fix Kconfig.debug "its" grammar

Use the possessive "its" instead of the contraction "it's"
where appropriate.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220715015959.12657-1-rdunlap@infradead.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

lib/Kconfig.debug

@@ -1560,7 +1560,7 @@ config DEBUG_KOBJECT_RELEASE
 	help
 	  kobjects are reference counted objects.  This means that their
 	  last reference count put is not predictable, and the kobject can
-	  live on past the point at which a driver decides to drop it's
+	  live on past the point at which a driver decides to drop its
 	  initial reference to the kobject gained on allocation.  An
 	  example of this would be a struct device which has just been
 	  unregistered.