Read entire HNVRAM partition space available

Also includes
  a) halve size of HNVRAM_RW partition (to match c/79795)
  b) only read from HNVRAM_RWB on failure to read HNVRAM_RW
  c) update hnvram code to use partition offsets from ruby_partitions.h.

Change-Id: I5576916b36742a2ae8cf98bf756efea1700ae58b
2 files changed