. initial workaround for assert() firing on iovec
size on ARM. likely due to alloc_contig() allocating
unusually mapped memory in STATICINIT.
. for the same reason use the regular cache i/o functions
to read the superblock in mfs - avoid the alloc_contig()
that STATICINIT does.
Change-Id: I3d8dc635b1cf2666e55b0393feae74cc25b8fed4