zynq: Use full tftpboot command instead of shortcut tftp

The reason is enabling tftpput command where
tftp shorcut stops to work for tftpboot.
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>

include/configs/zynq-common.h

@@ -164,7 +164,7 @@
 		"fatload mmc 0 ${load_addr} ${fit_image} && " \
 		"bootm ${load_addr}\0" \
 	"jtagboot=echo TFTPing FIT to RAM... && " \
-		"tftp ${load_addr} ${fit_image} && " \
+		"tftpboot ${load_addr} ${fit_image} && " \
 		"bootm ${load_addr}\0"
 #define CONFIG_BOOTCOMMAND		"run $modeboot"
 #define CONFIG_BOOTDELAY		3 /* -1 to Disable autoboot */