Revert "of: reserved-memory: Fix using wrong number of cells to get property 'alignment'"

This reverts commit bcf0fb1a due to
breaking parsing of reserved memory with the `alignment` property when
reserved memory defines the `alignment` property with
`#address-cells != #size-cells`. RobH plans to revert this change as
well [1]. Let's preemptively revert this in GKI to not break any
downstream devices in the meantime.

[1] https://lore.kernel.org/lkml/20250226194505.GA3407277-robh@kernel.org/



Bug: 399400888
Change-Id: I276e47a7f133f9d4196d853801581b5dec809b99
Signed-off-by: Will McVicker <willmcvicker@google.com>