sysvinit-inittab_2.88dsf.bb: only run serial checks at boot if we have items to check

sysvinit-inittab_2.88dsf.bb: only run serial checks at boot if we have items to check

Right now, we delay running the serial console checks to we boot up. This causes
issues for read only file systems. So, if have not configured any serial ports to
check via SERIAL_CONSOLES_CHECK we can skip the check at boot. This fixes any
issues with read only file systems and ipk packaging.

(From OE-Core rev: 019a95a5e01bd3fefaaab0a27029ed8b26ee3c79)

Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>