ipq806x: really fix aliases node for Qualcomm IPQ8064/DB149

ipq806x: really fix aliases node for Qualcomm IPQ8064/DB149

Having looked at this again, it appears that only gsbi2_serial
is actually enabled for this device, so the entry in the broken
aliases node was correct.

Therefore, this needs to set its own serial0 instead of inheriting
"serial0 = &gsbi4_serial;" from DTSI. Do this with the correctly
named aliases node now.

Fixes: c83f7b6d217f ("ipq806x: fix aliases node name for Qualcomm
IPQ8064/DB149")

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>