kernel-doc: fix plist.h comments

kernel-doc: fix plist.h comments

Make kernel-doc comments match macro names.
Correct parameter names in a few places.
Remove '#' from beginning of kernel-doc comment macro names.
Remove extra (erroneous) blank lines in kernel-doc.

Warning(plist.h:100): Cannot understand  * #PLIST_HEAD_INIT - static struct plist_head initializer on line 100 - I thought it was a doc line
Warning(plist.h:112): Cannot understand  * #PLIST_NODE_INIT - static struct plist_node initializer on line 112 - I thought it was a doc line
Warning(plist.h:103): No description found for parameter '_lock'
Warning(plist.h:129): No description found for parameter 'lock'
Warning(plist.h:158): No description found for parameter 'pos'
Warning(plist.h:169): No description found for parameter 'pos'
Warning(plist.h:169): No description found for parameter 'n'
Warning(plist.h:179): No description found for parameter 'mem'

This still leaves one warning & one error that need attention:
Error(plist.h:219): cannot understand prototype: '('
Warning(plist.h): no structured comments found

Acked-by: Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
Cc: Daniel Walker <dwalker@mvista.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>