pl010: Convert CONFIG_PL010_SERIAL to Kconfig

We want to use Kconfig logic to depend on whether pl01x devices
are built in, so let's convert their inclusion selection to Kconfig.

This round goes to pl010.

Signed-off-by: Alexander Graf <agraf@suse.de>

include/configs/edb93xx.h

@@ -80,7 +80,6 @@
 #define CONFIG_SYS_CBSIZE		1024	/* Console I/O buffer size */
 
 /* Serial port hardware configuration */
-#define CONFIG_PL010_SERIAL
 #define CONFIG_CONS_INDEX		0
 #define CONFIG_SYS_BAUDRATE_TABLE	{9600, 19200, 38400, 57600, \
                         115200, 230400}