net: dhcp6: pxe: Add DHCP/PXE commands for IPv6

Adds commands to support DHCP and PXE with IPv6.

New configs added:
- CMD_DHCP6
- DHCP6_PXE_CLIENTARCH
- DHCP6_PXE_DHCP_OPTION
- DHCP6_ENTERPRISE_ID

New commands added (when IPv6 is enabled):
- dhcp6
- pxe get -ipv6
- pxe boot -ipv6

Signed-off-by: Sean Edmond <seanedmond@microsoft.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/boot/pxe_utils.c b/boot/pxe_utils.c
index 3a1e50f..d13c47d 100644
--- a/boot/pxe_utils.c
+++ b/boot/pxe_utils.c
@@ -1578,7 +1578,7 @@
 
 int pxe_setup_ctx(struct pxe_context *ctx, struct cmd_tbl *cmdtp,
 		  pxe_getfile_func getfile, void *userdata,
-		  bool allow_abs_path, const char *bootfile)
+		  bool allow_abs_path, const char *bootfile, bool use_ipv6)
 {
 	const char *last_slash;
 	size_t path_len = 0;
@@ -1588,6 +1588,7 @@
 	ctx->getfile = getfile;
 	ctx->userdata = userdata;
 	ctx->allow_abs_path = allow_abs_path;
+	ctx->use_ipv6 = use_ipv6;
 
 	/* figure out the boot directory, if there is one */
 	if (bootfile && strlen(bootfile) >= MAX_TFTP_PATH_LEN)