of: add early boot allocation of of_find_node_by_phandle() cache

From: Frank Rowand <frank.rowand@sony.com>

The initial implementation of the of_find_node_by_phandle() cache
allocates the cache using kcalloc().  Add an early boot allocation
of the cache so it will be usable during early boot.  Switch over
to the kcalloc() based cache once normal memory allocation
becomes available.

Change-Id: I6acc88175ba9e4e17107d2f8a0cfd819a079f4d2
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Patch-mainline: linux-kernel @ 02/15/18, 06:22
[cpandya@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>