[roll] Roll fuchsia [kernel][vdso] Split private.h into multiple headers

Splits private.h into multiple headers:
1. data-constants.h: Contains the include directive for the vdso
   constants and the associated extern variable.
2. data-time-values.h: Contains the include directive for the TimeValues
   and the associated extern variable.
3. private.h: Contains the rest of the existing private.h header.

This was done to avoid the macro redefinition error surfaced by
https://fxrev.dev/1058852. That change attempts to add an atomic
suspend_offset field to the TimeValues structure. Unfortunately, this
causes a macro redefinition error on PAGE_SIZE, as seen in these two
builds from that CL:
* http://ci.chromium.org/b/8746291505332364609
* http://ci.chromium.org/b/8746291505332364593

In short, the issue is as follows:
1. The <atomic> header file transitively includes
   zircon/third_party/ulib/musl/include/bits/limits.h, which defines
   PAGE_SIZE as 4096.
2. The <arch/defines.h> header included in vdso-constants.h also defines
   PAGE_SIZE, but defines it as (1 << PAGE_SIZE_SHIFT) on both ARM and
   RISC-V.
So, vdso-constants.h and fasttime/internal/abi.h cannot be included in
the same file, which currently happens in private.h.

Luckily, all vDSO functions only require one of the two headers, so I
just split them out.

Original-Bug: 341785588
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1058853
Original-Revision: 9af597967989de001b62033290bf9fdf644eac67
GitOrigin-RevId: 08bd9e1adcb724a6cf713dbc60a73b09987fdebe
Change-Id: I7d3c2bf66f85162cf8a1b0e1cf895e6d86e16a48