I skipped the following files because they were not simple.
I'll create separate PRs.
arch/xtensa/src/esp32/esp32_cpustart.c
arch/xtensa/src/common/xtensa_abi.h
boards/xtensa/esp32/esp32-core/include/board.h
Also, I skipped the following files and directories because
they looked too huge and/or foreign.
arch/xtensa/include/esp32/tie.h
arch/xtensa/include/xtensa/xtensa_corebits.h
arch/xtensa/src/esp32/hardware/
arch/xtensa/include/esp32/tie-asm.h
arch/xtensa/include/esp32/core-isa.h
arch/xtensa/include/xtensa/core.h
I also fixed a few "is is" style typos when unwrapping long lines.
sched/init/nx_bringup.c: Fix a naming collision.
sched/init: Rename os_start() to nx_start()
sched/init: Rename os_smp* to nx_smp*
sched/init: Rename os_bringup to nx_bringup
sched/init: rename all internal static functions to begin with nx_ vs os_