net: lwip: add DHCP support and dhcp commmand

Add what it takes to enable NETDEVICES with NET_LWIP and enable DHCP as
well as the dhcp command. CMD_TFTPBOOT is selected by BOOTMETH_EFI due
to this code having an implicit dependency on do_tftpb().

Note that PXE is likely non-fonctional with NET_LWIP (or at least not
100% functional) because DHCP option 209 is not supported by the lwIP
library. Therefore, BOOTP_PXE_DHCP_OPTION cannot be enabled.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Tested-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/lib/tiny-printf.c b/lib/tiny-printf.c
index 64dee77..cc1dfe6 100644
--- a/lib/tiny-printf.c
+++ b/lib/tiny-printf.c
@@ -269,7 +269,8 @@
 				}
 				break;
 			case 'p':
-				if (CONFIG_IS_ENABLED(NET) || _DEBUG) {
+				if (CONFIG_IS_ENABLED(NET) ||
+				    CONFIG_IS_ENABLED(NET_LWIP) || _DEBUG) {
 					pointer(info, fmt, va_arg(va, void *));
 					/*
 					 * Skip this because it pulls in _ctype which is