x86/mm: Fix kernel-doc descriptions of various pgtable methods

So 'make W=1' complains about a couple of kernel-doc descriptions
in our MM primitives in pgtable.c:

  arch/x86/mm/pgtable.c:623: warning: Function parameter or struct member 'reserve' not described in 'reserve_top_address'
  arch/x86/mm/pgtable.c:672: warning: Function parameter or struct member 'p4d' not described in 'p4d_set_huge'
  arch/x86/mm/pgtable.c:672: warning: Function parameter or struct member 'addr' not described in 'p4d_set_huge'
  ... so on

Fix them all up, add missing parameter documentation, and fix various spelling
inconsistencies while at it.

[ mingo: Harmonize kernel-doc annotations some more. ]

Signed-off-by: Shivank Garg <shivankg@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Link: https://lore.kernel.org/r/20250514062637.3287779-1-shivankg@amd.com