serial: sprd: Assign sprd_port after initialized to avoid wrong access

serial: sprd: Assign sprd_port after initialized to avoid wrong access

The global pointer 'sprd_port' may not zero when sprd_probe returns
failure, that is a risk for sprd_port to be accessed afterward, and
may lead to unexpected errors.

For example:

There are two UART ports, UART1 is used for console and configured in
kernel command line, i.e. "console=";

The UART1 probe failed and the memory allocated to sprd_port[1] was
released, but sprd_port[1] was not set to NULL;

In UART2 probe, the same virtual address was allocated to sprd_port[2],
and UART2 probe process finally will go into sprd_console_setup() to
register UART1 as console since it is configured as preferred console
(filled to console_cmdline[]), but the console parameters (sprd_port[1])
belong to UART2.

So move the sprd_port[] assignment to where the port already initialized
can avoid the above issue.

Fixes: b7396a38fb28 ("tty/serial: Add Spreadtrum sc9836-uart driver support")
Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lore.kernel.org/r/20230725064053.235448-1-chunyan.zhang@unisoc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>