serial: sprd: getting port index via serial aliases only

[ Upstream commit 4b7349cb4e26e79429ecd619eb588bf384f69fdb ]

This patch simplifies the process of getting serial port number, with
this patch, serial devices must have aliases configured in devicetree.

The serial port searched out via sprd_port array maybe wrong if we don't
have serial alias defined in devicetree, and specify console with command
line, we would get the wrong port number if other serial ports probe
failed before console's. So using aliases is mandatory.

Reviewed-by: Baolin Wang <baolin.wang7@gmail.com>
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lore.kernel.org/r/20200318105049.19623-2-zhang.lyra@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: f9608f188756 ("serial: sprd: Assign sprd_port after initialized to avoid wrong access")
Signed-off-by: Sasha Levin <sashal@kernel.org>