lisa.utils: Move around sphinx_register_nitpick_ignore()
lisa.utils: Move around sphinx_register_nitpick_ignore()

Move sphinx_register_nitpick_ignore() to the beginning of the file, so
that other utils function can use it.

ARM-software/lisa,ARM-software/lisa,ARM-software/lisa,ARM-software/lisa,credp/lisa,credp/lisa,credp/lisa,credp/lisa