[PATCH 17/19] powerpc/vdso: Prepare introduction of struct vdso_clock

[Thomas Weißschuh]

From: Nam Cao <namcao at linutronix.de>

To support multiple PTP clocks, the VDSO data structure needs to be
reworked. All clock specific data will end up in struct vdso_clock and in
struct vdso_time_data there will be array of it. By now, vdso_clock is
simply a define which maps vdso_clock to vdso_time_data.

To prepare for the rework of the data structures, replace the struct
vdso_time_data pointer with struct vdso_clock pointer whenever applicable