serial: sprd: adjust TIMEOUT to a big value

BugLink: https://bugs.launchpad.net/bugs/1826212

commit e1dc9b08 upstream.

SPRD_TIMEOUT was 256, which is too small to wait until the status
switched to workable in a while loop, so that the earlycon could
not work correctly.
Signed-off-by: Wei Qiao <wei.qiao@spreadtrum.com>
Signed-off-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/tty/serial/sprd_serial.c

@@ -36,7 +36,7 @@
 #define SPRD_FIFO_SIZE		128
 #define SPRD_DEF_RATE		26000000
 #define SPRD_BAUD_IO_LIMIT	3000000
-#define SPRD_TIMEOUT		256
+#define SPRD_TIMEOUT		256000
 
 /* the offset of serial registers and BITs for them */
 /* data registers */