first_stage_init: support kernel module directories

Kernel modules may be located within directories in /lib/modules.
Attempt to load kernel modules from each directory that has a name starting with
the major and minor version of the currently running kernel. If a single
kernel module is successfully loaded from a directory, that directory is
treated as the correct kernel module directory for the system. No other
kernel module directories are searched and any kernel module load errors
in that directory are fatal. If the attempt to load the first kernel
module from a directory fails, or if there are no kernel modules in a
directory, then the search proceeds to the next directory.

If no kernel module is successfully loaded from any directory as above,
an attempt is made to load kernel modules from the top level at
/lib/modules/.

Bug: 157645635
Change-Id: I92eadd8617f03a645da460ccb776bc04fa541f00