Load kernel modules from /lib/modules/`uname -r`_$(page_size) if present

To support booting from both 4k/16k kernels, init need to tell which
kernel we are currently booting and load the right modules. To resolve
this issue, we store 16K modules into /lib/modules/`uname -r`_16k
directory.

Test: th
Bug: 293313353
Change-Id: I4a8296384537a71e16cd20e76e6c5dfb9074f574