UPSTREAM: net/tftp: fix build if CMD_BOOTEFI is not set

Fixes:
net/tftp.c:811: undefined reference to `efi_set_bootdev'

Change-Id: Ic4457c16228d03d8202cdab618f3178f5556610b
Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
(cherry picked from commit 64b8d7a677ce625c7dd30c040b32b606aea61745)

net/tftp.c

@@ -805,7 +805,9 @@ void tftp_start(enum proto_t protocol)
 		printf("Load address: 0x%lx\n", load_addr);
 		puts("Loading: *\b");
 		tftp_state = STATE_SEND_RRQ;
+#ifdef CONFIG_CMD_BOOTEFI
 		efi_set_bootdev("Net", "", tftp_filename);
+#endif
 	}
 
 	time_start = get_timer(0);