scsi: target: iscsi: Remove unused macro TEXT_LEN

Remove unused macro to fix the following compilation warning:

drivers/target//iscsi/iscsi_target_nego.c:31: warning: macro "TEXT_LEN" is not used [-Wunused-macros]
	#define TEXT_LEN 4096

Link: https://lore.kernel.org/r/20210228055645.22253-11-chaitanya.kulkarni@wdc.comReviewed-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/target/iscsi/iscsi_target_nego.c

@@ -28,7 +28,6 @@
 #include "iscsi_target_auth.h"
 
 #define MAX_LOGIN_PDUS  7
-#define TEXT_LEN	4096
 
 void convert_null_to_semi(char *buf, int len)
 {