[tip: timers/vdso] vdso/datastore: Allocate data pages dynamically

[Lad Prabhakar]

This commit breaks boot on Renesas arm64 RZ/V2H and RZ/V2N platforms.

The boot process doesn't complete anymore with no obvious error logs to
indicate the cause of the failure.

Reverting the following two commits fixes the boot issue:
  10d91dac2ea5 ("vdso/datastore: Allocate data pages dynamically")
  6a011a228293 ("vdso/datastore: Map pages through struct page")

Cheers,
Prabhakar