first_stage_init: run first_stage.sh regardless of console presence

To enable the use of first_stage.sh on target configurations that lack a
console, run it regardless of whether a console has been specified on
the kernel command line. The first stage console is still only opened if
a console is present.

Bug: 163857097
Change-Id: I5f8bb66cbb42006e4b2710e17504844e665219f4