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/[e-mail]
Reviewed-by: Mike Christie <[e-mail]>
Reviewed-by: Johannes Thumshirn <[e-mail]>
Signed-off-by: Chaitanya Kulkarni <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/target/iscsi/iscsi_target_nego.c

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